98 results
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2. Quantitative Analysis of the Synergy of Doping and Nanostructuring of Oxide Photocatalysts.
- Author
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Seriani, Nicola, Delcompare-Rodriguez, Paola, Pandey, Dhanshree, Adak, Abhishek Kumar, Mahamiya, Vikram, Pinilla, Carlos, and El-Khozondar, Hala J.
- Subjects
ELECTRIC potential ,ENERGY conversion ,TRANSITION metal oxides ,ELECTRIC fields ,METALLIC oxides - Abstract
In this paper, the effect of doping and nanostructuring on the electrostatic potential across the electrochemical interface between a transition metal oxide and a water electrolyte is investigated by means of the Poisson–Boltzmann model. For spherical nanoparticles and nanorods, compact expressions for the limiting potentials at which the space charge layer includes the whole semiconductor are reported. We provide a quantitative analysis of the distribution of the potential drop between the solid and the liquid and show that the relative importance changes with doping. It is usually assumed that high doping improves charge dynamics in the semiconductor but reduces the width of the space charge layer. However, nanostructuring counterbalances the latter negative effect; we show quantitatively that in highly doped nanoparticles the space charge layer can occupy a similar volume fraction as in low-doped microparticles. Moreover, as shown by some recent experiments, under conditions of high doping the electric fields in the Helmholtz layer can be as high as 100 mV/Å, comparable to electric fields inducing freezing in water. This work provides a systematic quantitative framework for understanding the effects of doping and nanostructuring on electrochemical interfaces, and suggests that it is necessary to better characterize the interface at the atomistic level. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Effect of non-metal doping on the optoelectronic properties of ZrS2/ZrSe2 heterostructure under strain: a first-principles study.
- Author
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Zhao, Yanshen, Yang, Lu, Sun, Shihang, Wei, Xingbin, and Liu, Huaidong
- Subjects
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PERIODIC motion , *ENERGY levels (Quantum mechanics) , *BAND gaps , *DENSITY functionals , *PSEUDOPOTENTIAL method - Abstract
Context: In this paper, we systematically studied the effects of non-metallic element (B, C, N, O, F) doping and biaxial stretching on the photoelectric properties of ZrS2/ZrSe2 heterostructures by using the first-principles calculation method based on density functional theory. The results show that the p-type doping is realized by B, C, and N atom doping, and the n-type doping is realized by O and F atom doping. The doping of B and C atoms produces impurity energy levels in the band gap, which affects the conductivity of the heterostructure. The band gap of N and O atom–doped heterostructures increases under tensile strain, but it is still a direct band gap. The analysis of the optical properties of the heterostructures shows that the doping of non-metallic atoms can adjust the optical absorption rate and reflectivity of the heterostructures. Under the action of tensile strain, the optical properties of the doped heterostructures have changed significantly in the low-energy region. This article provides a theoretical basis for the future application of ZrS2/ZrSe2 heterostructures. Method: This paper uses the first-principles calculation method based on density functional theory. The PBE exchange-correlation functional based on generalized gradient approximation (GGA) is selected for the specific calculation, and the crystal structure is geometrically optimized by the ultrasoft pseudopotential method. It is verified that when the cutoff energy of the ZrS2/ZrSe2 heterostructure is 500 eV, the K-point grid is selected to be 10 × 10 × 2 with the lowest energy, so the cutoff energy is selected to be 500 eV. The K-point grid is selected to be 10 × 10 × 2. The convergence limits for structural optimization are as follows: the maximum force between atoms is 0.01 eV/Å, the convergence threshold of the maximum energy change is set to 10−9 eV/atom, and the convergence threshold of the maximum displacement is 0.001 Å. In order to avoid the influence of atomic periodic motion between different atomic layers, a vacuum layer of 20 Å is added in the vertical direction. Considering the interaction of vdW between the interfaces, the DFT-D2 method is used to verify. The optical properties were calculated by the random phase approximation method, and the K-point grid was selected as 12 × 12 × 2. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Thermal Stability and High-Temperature Super Low Friction of γ-Fe 2 O 3 @SiO 2 Nanocomposite Coatings on Steel.
- Author
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Zeng, Qunfeng
- Subjects
THERMAL stability ,PHASE transitions ,NANOCOMPOSITE materials ,SURFACE coatings ,FRICTION - Abstract
The thermal stability of the γ-Fe
2 O3 @SiO2 nanocomposites and super low friction of the γ-Fe2 O3 @SiO2 nanocomposite coatings in ambient air at high temperature are investigated in this paper. X-ray diffraction, scanning electron microcopy, transmission scanning electron microcopy, high-temperature tribometer, thermogravimetric analysis and differential scanning calorimetry were used to investigate the microstructure, surface morphology and high-temperature tribological properties of the γ-Fe2 O3 @SiO2 nanocomposite coatings, respectively. The results show that the γ-Fe2 O3 @SiO2 nanocomposite with the core–shell structure has excellent thermal stability because the SiO2 shell inhibits the phase transition of the γ-Fe2 O3 phase to the α-Fe2 O3 phase in the nanocomposites. The temperature of the phase transition in γ-Fe2 O3 can be increased from 460 to 829 °C. The γ-Fe2 O3 @SiO2 nanocomposite coatings exhibit super low friction (0.05) at 500 °C. A high-temperature super low friction mechanism is attributed to γ-Fe2 O3 and the tribochemical reactions during sliding. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
5. Effect of non-metal doping on the optoelectronic properties of ZrS2/ZrSe2 heterostructure under strain: a first-principles study
- Author
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Zhao, Yanshen, Yang, Lu, Sun, Shihang, Wei, Xingbin, and Liu, Huaidong
- Published
- 2024
- Full Text
- View/download PDF
6. Adsorption of Zn atoms by monolayer WS2 doped with different atoms X (X = O, Se, N, P, F, Cl): first principles study.
- Author
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Mu, Yansong, Liu, Guili, Su, Dan, Yang, Zhonghua, and Zhang, Guoying
- Subjects
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ENERGY level densities , *DOPING agents (Chemistry) , *ATOMIC models , *FERMI energy , *DIELECTRIC function - Abstract
Context: The effect of X (X = O, Se, N, P, F, Cl) doping on the adsorption of Zn atoms by WS2 was investigated based on first principles. The electronic structure and optical properties of the adsorbed system after atomic doping were calculated. It is found that the Zn atom adsorbed on the W top (Tw) site has the most stable structure. When an S atom is replaced with an X atom based on the adsorption system, where the adsorption energy decreases after doping of O, P, F, and Cl atoms compared to the undoped system, it means that each system is more stable after doping of these atoms; charge transfer shows that the adsorption system after P-atom doping the system around the Zn atom loses electrons while S-atom gains electrons, which indicates that P-atom doping is favorable for the adsorption of Zn by WS2, N, P-atom is introduced as p-type doping and F, Cl-atom is introduced undoped by n-type doping, and the band gap of the doped system is less than that of the undoped one. With the introduction of different dopant atoms, certain impurity energy levels are introduced into the adsorption system. The prohibited bandwidth around the Fermi energy level reduces the density of states, causing the doped system's density of states to shift to lower energies, among which the shifts of N, P, F, and Cl are more pronounced. The P-doped adsorption system shows a new peak near the energy of − 11 eV. In addition, the study of optical properties showed that the peak reflections of both doped and non-doped systems adsorbing Zn atoms appeared in the ultraviolet region; the absorbance coefficient of the doped system is moved in the lower energy direction and red-shifted after atom doping; in addition, the absorption coefficients and reflectance of the P, Se doped systems are enhanced in the wavelength range of 200–300 nm compared with that before doping, the dielectric function and CBM and VBM positions were also calculated further indicating the potential of Se-doped systems in improving photocatalytic efficiency. Methods: In this paper, the structure optimization of X (X = O, Se, N, P, F, Cl) doping on WS2 adsorbed Zn atom model is performed based on the CASTEP module in Materials-Studio software under the first principles using GGA and PBE generalized function. The corresponding binding energies, bond lengths, bond angles, charge densities, energy band structures, densities of states, and optical properties were also analyzed. The Monkhorst–Pack particular K-point sampling method is used in the calculations; the K-point grid is 6 × 6 × 1, and the cutoff energy for the plane wave expansion is 500 eV. After geometric optimization, the iterative accuracy converges to a value of less than 1 × 10−5 eV/atom for the total energy of each atom and less than 0.03 eV/Å for all atomic forces. The thickness of the vacuum layer was set to 20 Å to avoid the effect of interlayer interaction forces. In this paper, 27 atoms were used to form a 3 × 3 × 1 supercellular tungsten disulfide system consisting of 18 S atoms and 9 W atoms. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Preparation of High-Efficiency Fe/N-Doped Carbon Catalysts Derived from Graphite Phase Carbon Nitride for Reduction of Oxygen.
- Author
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Wang, Yan, Liu, Wuxin, Wang, Rongzhe, Wang, Qing, Luo, Shaohua, Hou, Pengqing, Zhang, Yahui, Yan, Shengxue, Liu, Xin, and Guo, Jing
- Subjects
OXYGEN reduction ,GRAPHITE ,HYDROGEN evolution reactions ,NITRIDES ,CATALYSTS ,CARBON ,ELECTROCATALYSTS ,MELAMINE - Abstract
Fe/N-doped carbon (Fe-NC) is an excellent base-metal catalyst for use in an electrocatalytic oxygen reduction reaction (ORR) with high activity. In this paper, graphite phase carbon nitride (g-C
3 N4 ) was first obtained from the pyrolyzing of melamine, and then different proportions of FeCl3 were separately doped into g-C3 N4 to further prepare the Fe-NC catalyst. The Fe-NC catalyst was applied in an ORR reaction, and the results show that the Fe-NC catalyst doped with 0.5 mmol FeCl3 possesses exceptional electrocatalytic performance, with an onset potential of 0.96 V and a half-wave potential of 0.81 V, which approaches that of a Pt/C catalyst. Meanwhile, the Fe-NC catalyst displays high stability and methanol resistance. The results supply a new way to prepare efficient ORR electrocatalysts. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
8. MORPHOLOGY OF THE SURFACE OF SILICON DOPED WITH LUTETIUM.
- Author
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Daliev, Khodjakbar S., Utamuradova, Sharifa B., Khamdamov, Jonibek J., and Bahronkulov, Zavkiddin E.
- Subjects
SURFACE morphology ,SILICON ,LUTETIUM ,SCANNING electron microscopes ,SEMICONDUCTOR doping - Abstract
In this paper, using a scanning electron microscope (SEM) and atomic analysis, the location map of microcomposites formed on the surface of n-Si, p-Si, n-Si
and p-Si samples was studied. Force microscope (AFM) research devices. The atomic fractions of inclusions of carbon, oxygen and lutetium formed on the surface of the samples were studied. Also, using the ASM device, the sizes, relief and topographic appearance of defects formed on the surface of the samples were determined. In silicon samples doped with Lu, a decrease in the size of surface defects and the formation of nano-sized structures were found, which makes it possible to obtain materials with a more perfect crystal structure. Using a ZEISS GeminiSEM 300 scanning electron microscope, the structural structure, chemical composition and images of their arrangement of n-Si, p-Si, n-Si and p-Si samples were obtained. In this case, the electron accelerating voltage was 20 kV, and the pressure in the sample chamber was (10-3 mmHg). Research results show that the structural structure of microand nanocomposites formed in silicon mainly depends on the diffusion time and cooling rate of the samples after diffusion annealing. [ABSTRACT FROM AUTHOR] - Published
- 2024
- Full Text
- View/download PDF
9. Pure and (Sn or Mg) Doped GeFe 2 O 4 as Anodes for Sodium-Ion Batteries.
- Author
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Ambrosetti, Marco, Quinzeni, Irene, Girella, Alessandro, Berbenni, Vittorio, Albini, Benedetta, Galinetto, Pietro, Sturini, Michela, and Bini, Marcella
- Subjects
ANODES ,SODIUM ions ,LITHIUM-ion batteries ,CRYSTAL structure ,SPINEL ,TIN ,ELECTRIC batteries - Abstract
GeFe
2 O4 (GFO) is a germanium mineral whose spinel crystal structure determines its interesting functional properties. Recently, it was proposed for application as an anode for Sodium and Lithium-Ion Batteries (SIBs and LIBs) thanks to its combined conversion and alloying electrochemical mechanism. However, its entire potential is limited by the poor electronic conductivity and volumetric expansion during cycling. In the present paper, pure and Sn or Mg doped GFO samples obtained from mechano-chemical solid-state synthesis and properly carbon coated were structurally and electrochemically characterized and proposed, for the first time, as anodes for SIBs. The spinel cubic structure of pure GFO is maintained in doped samples. The expected redox processes, involving Fe and Ge ions, are evidenced in the electrochemical tests. The Sn doping demonstrated a beneficial effect on the long-term cycling (providing 150 mAh/g at 0.2 C after 120 cycles) and on the capacity values (346 mAh/g at 0.2 C with respect to 300 mAh/g of the pure one), while the Mg substitution was less effective. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
10. Halogen modified organic porous semiconductors in photocatalysis: mechanism, synthesis, and application.
- Author
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Yue Yang, Liping Guo, Xuepeng Wang, Zhenzi Li, and Wei Zhou
- Subjects
HALOGENS ,SEMICONDUCTORS ,PHOTOCATALYSIS ,CHARGE transfer ,ELECTRONS - Abstract
Photocatalysis is considered as the promising energy conversion way to resolve the issues of energy crisis and environmental pollution. As the key point of the photocatalysis, the photocatalyst determines the final conversion efficiency from solar, therefore, the composition and photoelectronic nature of which deserve to be valued. Halogen often affects immensely the intrinsic electron configuration of the matrix because of electrophilic property, and thus its topic has attracted lots of attention for photocatalytic application. In this review, halogencontained organic porous semiconductors are discussed in detailed. Firstly, the role of halogens in photocatalysis based on organic porous semiconductors are categorized. Then, the way to introduce the halogens into organic porous semiconductors and their applications in photocatalysis are reviewed. At last, the outlooks are given at the end of this paper. This review would bring new insights into the non-metal doping engineering for improving the photocatalytic performance of organic semiconductors. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. First-principles study of the effects of doping B, N, and O on the photoelectric properties of Cr adsorbed GaS.
- Author
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Yang, Xiaotong, Liu, Guili, He, Jianlin, Wei, Ran, Ma, Mengting, Xu, Jingze, Zhao, Bingcai, Ru, Yunfan, Yang, Zhonghua, and Zhang, Guoying
- Subjects
- *
THEORY of distributions (Functional analysis) , *GAS absorption & adsorption , *NUCLEAR forces (Physics) , *GEOMETRIC modeling , *ELECTRONIC structure , *BORON - Abstract
Context: To lessen the impact of the dangerous metal Cr, this paper applies the first principles to investigate the adsorption behavior and photoelectric properties of GaS on Cr. The effects of doped GaS on Cr adsorption behavior are investigated with four GaS systems, which are pure, boron (B)-doped, nitrogen (N)-doped, and oxygen (O)-doped, in order to maximize the characteristics of GaS for use in novel sectors, to obtain understanding of the impact of doping on the electronic structure and optical properties of GaS adsorption of Cr, as well as to promote the development of the material. Four GaS adsorbed Cr systems, pure, B-doped, N-doped, and O-doped, are optimized, and the optimized results show that the stable adsorption position of Cr on both pure and doped GaS is the top position of Ga atoms, whereas doped elements B, N, and O can promote the adsorption of Cr on GaS, and the order of the strength of this promotion is B > N > O. Method: In this paper, molecular simulation calculations and analyses using the CASTEP module in the software Materials Studio are performed to simulate the structure optimization of GaS-adsorbed Cr materials doped with B, N, and O atoms by using the generalized gradient approximation (GGA) plane-wave pseudopotential approach [1] and the Perdew-Burke-Ernzerhof (PBE) generalized function [2]. From the convergence test, it is reasonable to set the K-point network to 4 × 4 × 1 and the truncation energy to 500 eV [3]. In this paper, a 3 × 3 × 1 supercell structure with 18 S atoms and 18 Ga atoms is selected. The convergence value of the iterative accuracy is 1.0e − 5 eV/atom, and all the atomic forces are less than 0.02 eV/Å. A vacuum layer of 16 Å is also set in the C direction to avoid interlayer interactions of GaS. First, we optimize the geometry of the model and then analyze the nature of the adsorption energy and electronic structure corresponding to the model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. Interfacial engineering of 2H-MoS2/N-doped carbon composite for fast potassium interfacial storage.
- Author
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Wang, Xu, Zhang, Panpan, Lu, Chunsheng, Li, Xiaowei, Dou, Aichun, Hou, Xiaochuan, and Liu, Yunjian
- Abstract
The 2H-MoS
2 incorporated with N-doped carbon (2H-MoS2 /NC) with high discharge capacity has attracted more research focus as an anode material for K-ion batteries (PIBs). However, large longitudinal lattice deformation at 2H-MoS2 /NC heterointerfaces caused by interfacial intercalation of K ions negatively impacts the structural stability, which limits its cycling performance. In this paper, interfacial engineering has been applied to optimize the structural stability of 2H-MoS2 /NC. By using first-principle simulation, the evolutions of longitudinal lattice deformation, K adsorption/diffusion performance/behaviour, interfacial strength, and electronic property with the interfacial interlayer spacing have been systematically explored. The results show that with the increase of interlayer spacing from 5.0 to 7.0 Å, the lattice deformation, interfacial strength, and K adsorption kinetics first decrease sharply with interlayer spacing in the range of 5.0–6.5 Å, and then they drop minorly at 6.5–7.0 Å. The K interfacial diffusion capability can be improved due to the decreased charge accumulation at interface that leads to weakened K–S bonding with a rising interlayer spacing. Based on variation of structural stability and K storage performance, an optimal interlayer spacing of 6.75 Å is confirmed. These findings can provide a solid theoretical basis and guidance for the experimental preparation of high-performance 2H-MoS2 /NC electrode materials and further cultivate new concepts for the optimal design of two-dimensional composite electrode materials. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
13. Adsorption of Zn atoms by monolayer WS2 doped with different atoms X (X = O, Se, N, P, F, Cl): first principles study
- Author
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Mu, Yansong, Liu, Guili, Su, Dan, Yang, Zhonghua, and Zhang, Guoying
- Published
- 2024
- Full Text
- View/download PDF
14. Effects of length, diameter, and doping on the thermal transport in carbon nanotubes: a molecular dynamics study.
- Author
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Ebin, P. S. and Babu, Jeetu S.
- Subjects
CARBON nanotubes ,MOLECULAR dynamics ,THERMAL conductivity ,THERMOELECTRIC apparatus & appliances ,PHONON scattering ,THERMAL insulation - Abstract
In this study, we have investigated numerous influential factors such as length, diameter, impurity introduction, and vacancy defects on the thermal conductivity of carbon nanotubes (CNTs). These investigations were conducted through molecular dynamics simulations using the large-scale atomic/molecular massively parallel simulator (LAMMPS). It is observed that longer CNTs tend to exhibit heightened thermal conductivity, a consequence of the increased support for phonon vibration modes that facilitate efficient thermal transport. Furthermore, CNTs with larger diameters display superior thermal characteristics owing to reduced phonon scattering effects. The introduction of boron doping reduces CNTs thermal conductivity by approximately 3% with the inclusion of 6% boron atoms, whereas nitrogen doping increases it by a similar margin. These doping effects hold great potential for optimizing the performance of MEMS and NEMS devices. This duality in doping offers a versatile means to fine-tune the thermal conductivity of CNTs, enabling effective heat management in micro/nanodevices. By strategically modulating thermal conductivity, we can optimize the heat transfer properties of CNT-based materials and devices. This optimization is of utmost importance in ensuring efficient heat dissipation and averting thermal-induced issues, such as overheating, performance degradation, or failure. Additionally, this paper explores how vacancy defects impact the thermal conductivity of CNTs. By varying the vacancy concentration from 1 to 6%, a decrease in thermal conductivity of approximately 2% to 4% was observed in both SWCNTs and DWCNTs. These results emphasize the pivotal role of defects in perturbing the efficient phonon transport mechanisms in CNTs and suggest the potential for customizing CNTs with specific defect concentrations to enhance their suitability for thermoelectric devices and thermal insulation materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
15. Effect of Mn Substitution on GeFe 2 O 4 as an Anode for Sodium Ion Batteries.
- Author
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Ambrosetti, Marco, Rocchetta, Walter, Quinzeni, Irene, Milanese, Chiara, Berbenni, Vittorio, and Bini, Marcella
- Subjects
SODIUM ions ,INTERCALATION reactions ,STORAGE batteries ,SPINEL ,IONS - Abstract
GeFe
2 O4 (GFO), with its intriguing intercalation mechanism based on alloying–conversion reactions, was recently proposed as an anode material for sodium ion batteries (SIBs). However, drawbacks related to excessive volume expansion during intercalation/deintercalation and poor electronic conductivity enormously hinder its practical application in batteries. In this regard, some experimental strategies such as cation substitutions and proper architectures/carbon coatings can be adopted. In this paper, pure and Mn-doped GFO samples were prepared by hydrothermal synthesis. The doped samples maintained the spinel cubic structure and the morphology of pure GFO. The electrochemical tests of the samples, performed after proper carbon coating, showed the expected redox processes involving both Ge and Fe ions. The Mn doping had a positive effect on the capacity values at a low current density (about 350 mAh/g at C/5 for the Mn 5% doping in comparison to 300 mAh/g for the pure sample). Concerning the cycling stability, the doped samples were able to provide 129 mAh/g (Mn 10%) and 150 mAh/g (Mn 5%) at C/10 after 60 cycles. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
16. Tetrahedral Amorphous Carbon Coatings with Al Incorporation Deposited by a Hybrid Technique of Sputtering and Arc Evaporation.
- Author
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Dai, Wei, Shi, Yunzhan, Wang, Qimin, and Wang, Junfeng
- Subjects
AMORPHOUS carbon ,SURFACE coatings ,GRAPHITIZATION ,MECHANICAL wear ,RESIDUAL stresses ,CONCENTRATION functions ,VACUUM arcs - Abstract
In this paper, tetrahedral amorphous carbon (ta-C) coatings containing Al were deposited by a hybrid technique of sputtering and arc evaporation. The influence of Al incorporation in the structure and properties of the ta-C coatings were studied as a function of the Al concentration. It is found that Al tends to form a Al-O-C bond when the Al concentration is small. An Al-C bond was detected when the Al concentration is high. Al can facilitate the graphitization of the ta-C coatings and the graphite cluster size as well as the sp
2 /sp3 ratio of the coatings increase as the Al concentration increases. The decline of the sp3 fraction causes the drop in the hardness of the coatings. The incorporation of Al can effectively decrease the residual stress of the ta-C coatings. During friction tests, Al can facilitate the formation of the sp2 -rich graphitic tribo-layer and decrease the friction coefficient. Nevertheless, the decline of the hardness due to the Al incorporation will result in the increase in the wear rate of the coating. It is believed that the ta-C coating with a proper concentration of Al appears to achieve a good comprehensive performance with high hardness, low residual stress, and a low friction coefficient and wear rate. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
17. Modelling the Quantum Capacitance of Single-layer and Bilayer Graphene.
- Author
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AMMOUR, Yousra, REMMOUCHE, Riad, and FATES, Rachid
- Subjects
GRAPHENE ,ELECTRIC capacity ,GAUSSIAN distribution ,QUANTUM states - Abstract
In this paper, we report the modelling of quantum capacitance in both single-layer and bilayer graphene devices to investigate the temperature dependence. The model includes the existence of electron and hole puddles due to local fluctuations of the potential, which is taken into account with the possibility of finite lifetimes of electronic states to calculate the quantum capacitance using the Gaussian distribution. The results indicate that the simulations are in agreement with the experimental measurements, which proves the accuracy of the proposed model. On the other hand, temperature dependence around the charge neutrality point has been reported for both single and bilayer graphene. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
18. Interfacial engineering of 2H-MoS2/N-doped carbon composite for fast potassium interfacial storage
- Author
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Wang, Xu, Zhang, Panpan, Lu, Chunsheng, Li, Xiaowei, Dou, Aichun, Hou, Xiaochuan, and Liu, Yunjian
- Published
- 2024
- Full Text
- View/download PDF
19. Effect of compressive strain on electronic and optical properties of Cr-doped monolayer WS2.
- Author
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Mu, Yansong, Liu, Guili, Wei, Ran, and Zhang, Guoying
- Subjects
- *
BAND gaps , *OPTICAL properties , *MONOMOLECULAR films , *ELECTRONIC spectra , *DIELECTRIC function , *DENSITY functional theory , *ENERGY bands - Abstract
Context: The electronic properties and optical properties of Cr-doped monolayer WS2 under uniaxial compressive deformation have been investigated based on density functional theory. In terms of electronic structure properties, both intrinsic and doped system bandgaps decrease with the increase of compression deformation, and the values of the bandgap under the same compression deformation after Cr doping are reduced compared with the corresponding intrinsic states. When the compressive deformation reaches 10%, both the intrinsic and doped system band gaps are close to zero. New electronic states and impurity energy levels appear in the WS2 system when doped with Cr atoms. For the optical properties, the calculation and analysis of the dielectric function under each deformation regime of monolayer WS2 show that the compression deformation affects the dielectric function, and when the compression deformation is 10%, the un-doped and Cr-doped regimes show a decrease in ε1(ω) compared to the compression deformation of 8%. For each deformation system, the peak reflections occur in the ultraviolet region. Near the position where the second peak of the absorption spectrum appears, it can be seen that the ability of each system to absorb light gradually decreases with the increase of the amount of deformation and appears to be red-shifted to varying degrees. Methods: This study follows the initial principles of the density functional theory framework and is based on the CASTEP module of Materials-Studio software GGA and PBE generalizations are used to perform computations such as geometry optimization of the model. We have calculated the energy band structure of monolayer WS2 with intrinsic and compressive deformations of 2% and 4% using PBE and HSE06, respectively. The band gap values calculated using PBE are 1.802 eV, 1.663 eV, and 1.353 eV, respectively, and the band gap values calculated with HSE06 are 2.267 eV, 2.034 eV, 1.751 eV. The results show that the bandgap values calculated by HSE06 are significantly higher than those calculated by PBE, but the bandgap variations calculated by the two methods have the same trend, and the shape characteristics of the energy band structure are also the same. However, it is worth noting that the computation time required for the HSE06 calculation is much longer than that of the PBE, which is far beyond the capability of our computer hardware, and the purpose of this paper is to investigate the change rule of the effect of deformation on the bandgap value, so to save the computational resources, the next calculations are all calculated using the PBE. The Monkhorst–Pack special K-point sampling method is used in the calculations. The cutoff energy for the plane wave expansion is 400 eV, and the K-point grid is assumed to be 5 × 5 × 1. Following geometric optimization, the iterative precision converges to a value of less than 0.03 eV/Å for all atomic forces and at least 1 × 10−5 eV/atom for the total energy of each atom. The vacuum layer's thickness was selected at 20 Å to mitigate the impact of the interlayer contact force. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. Effect of compressive strain on electronic and optical properties of Cr-doped monolayer WS2.
- Author
-
Mu, Yansong, Liu, Guili, Wei, Ran, and Zhang, Guoying
- Subjects
BAND gaps ,OPTICAL properties ,MONOMOLECULAR films ,ELECTRONIC spectra ,DIELECTRIC function ,DENSITY functional theory ,ENERGY bands - Abstract
Context: The electronic properties and optical properties of Cr-doped monolayer WS
2 under uniaxial compressive deformation have been investigated based on density functional theory. In terms of electronic structure properties, both intrinsic and doped system bandgaps decrease with the increase of compression deformation, and the values of the bandgap under the same compression deformation after Cr doping are reduced compared with the corresponding intrinsic states. When the compressive deformation reaches 10%, both the intrinsic and doped system band gaps are close to zero. New electronic states and impurity energy levels appear in the WS2 system when doped with Cr atoms. For the optical properties, the calculation and analysis of the dielectric function under each deformation regime of monolayer WS2 show that the compression deformation affects the dielectric function, and when the compression deformation is 10%, the un-doped and Cr-doped regimes show a decrease in ε1 (ω) compared to the compression deformation of 8%. For each deformation system, the peak reflections occur in the ultraviolet region. Near the position where the second peak of the absorption spectrum appears, it can be seen that the ability of each system to absorb light gradually decreases with the increase of the amount of deformation and appears to be red-shifted to varying degrees. Methods: This study follows the initial principles of the density functional theory framework and is based on the CASTEP module of Materials-Studio software GGA and PBE generalizations are used to perform computations such as geometry optimization of the model. We have calculated the energy band structure of monolayer WS2 with intrinsic and compressive deformations of 2% and 4% using PBE and HSE06, respectively. The band gap values calculated using PBE are 1.802 eV, 1.663 eV, and 1.353 eV, respectively, and the band gap values calculated with HSE06 are 2.267 eV, 2.034 eV, 1.751 eV. The results show that the bandgap values calculated by HSE06 are significantly higher than those calculated by PBE, but the bandgap variations calculated by the two methods have the same trend, and the shape characteristics of the energy band structure are also the same. However, it is worth noting that the computation time required for the HSE06 calculation is much longer than that of the PBE, which is far beyond the capability of our computer hardware, and the purpose of this paper is to investigate the change rule of the effect of deformation on the bandgap value, so to save the computational resources, the next calculations are all calculated using the PBE. The Monkhorst–Pack special K-point sampling method is used in the calculations. The cutoff energy for the plane wave expansion is 400 eV, and the K-point grid is assumed to be 5 × 5 × 1. Following geometric optimization, the iterative precision converges to a value of less than 0.03 eV/Å for all atomic forces and at least 1 × 10−5 eV/atom for the total energy of each atom. The vacuum layer's thickness was selected at 20 Å to mitigate the impact of the interlayer contact force. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
21. Structural stability and electrical properties of (1-x)(Bi0.5Na0.5)TiO3-xBaTiO3 ceramic coatings.
- Author
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Zhu, Hefa, Wang, Haidou, Guo, Weiling, Peng, Wei, Mi, Qingbo, Dong, Han, and Xing, Zhiguo
- Subjects
- *
CERAMIC coating , *MORPHOTROPIC phase boundaries , *STRUCTURAL stability , *VALENCE fluctuations , *PLASMA spraying , *SURFACE roughness - Abstract
In this paper, (1- x)(Bi 0.5 Na 0.5)TiO 3 - x BaTiO 3 (x = 0, 0.06, 0.08, and 0.10) ceramic coatings were prepared by supersonic plasma spraying. Phase structure, microstructure, dielectric, ferroelectric, and piezoelectric properties of the (Bi 0.5 Na 0.5)TiO 3 ceramic coatings doped with BaTiO 3 were all thoroughly examined. According to the findings, all of the (1- x)(Bi 0.5 Na 0.5)TiO 3 - x BaTiO 3 ceramic coatings have a typical perovskite structure and form a morphotropic phase boundary (MPB) with rhombohedral and tetragonal phases coexisting in the x = 0.06–0.10 range. The coating's overall surface is uniformly flat, with a surface roughness (Sa) of less than 10 μm and a line roughness (Ra) of less than 2 μm. The coating has a homogeneous cross section, a well-integrated interface, a few pores and cracks, and a porosity of less than 6 %. With no obvious valence changes of the other elements, the results of XPS indicate a certain degree of breakdown during the spraying process, when Ti4+ changes to generate oxygen vacancy defects of Ti3+. The best electrical conductivity of the 0.92BNT-0.08BT coating has been found at x = 0.08, where the dielectric constant is 255 (0.02), the remnant polarization (P r) is 22.21 μC/cm2, the coercive field (E c) is 29.17 kV/cm, and the piezoelectric coefficient (d 33) is 35.1 pC/N. The (1- x)(Bi 0.5 Na 0.5)TiO 3 - x BaTiO 3 ceramic coating application space and range at high temperature are expanded when the temperature (T m) close to the maximum dielectric constant increases significantly reaching 431.2 °C. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
22. Mechanistic exploration of Co doping in optimizing the electrochemical performance of 2H-MoS2/N-doped carbon anode for potassium-ion battery.
- Author
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Zhang, Panpan, Wang, Xu, Yang, Yangyang, Yang, Haifeng, Lu, Chunsheng, Su, Mingru, Zhou, Yu, Dou, Aichun, Li, Xiaowei, Hou, Xiaochuan, and Liu, Yunjian
- Subjects
- *
ANODES , *TRANSITION metals , *ACTIVATION energy , *CARBON , *TRANSITION metal oxides , *STORAGE batteries - Abstract
[Display omitted] The 2H-MoS 2 /nitrogen-doped carbon (2H-MoS 2 /NC) composite is a promising anode material for potassium-ion batteries (PIBs). Various transition metal doping has been adopted to optimize the poor intrinsic electronic conductivity and lack of active sites in the intralayer of 2H-MoS 2. However, its optimization mechanisms have not been well probed. In this paper, using Cobalt (Co) as an example, we aim to investigate the influence of transition metal doping on the electronic and mechanical properties and electrochemical performance of 2H-MoS 2 /NC via first-principles calculation. Co doping is found to be effective in improving the electronic conductivity and the areas of active sites on different positions (C surface, interface, and MoS 2 surface) of 2H-MoS 2 /NC. The increased active sites can optimize K adsorption and diffusion capability/processes, where general smaller K adsorption energies and diffusion energy barriers are found after Co doping. This helps improve the rate performance. Especially, the pyridinic N (pyN), pyrrolic N (prN), and graphitic N (grN) are first unveiled to respectively work best in K kinetic adsorption, diffusion, and interfacial stability. These findings are instructive to experimental design of high rate 2H-MoS 2 /NC electrode materials. The roles of different N types provide new ideas for optimal design of other functional composite materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
23. First-principles study of the effect of doping on the optoelectronic properties of defective monolayers of MoSe2.
- Author
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Su, Dan, Liu, Guili, Ma, Mengting, Wei, Ran, Mu, Yansong, Yang, Zhonghua, and Zhang, Guoying
- Subjects
- *
PSEUDOPOTENTIAL method , *ELECTRONIC structure , *DIELECTRIC function , *CONDUCTION bands , *DENSITY of states , *MONOMOLECULAR films , *DENSITY functional theory , *ELECTRO-optical effects - Abstract
Context: In this paper, the structural stability, electronic structure, and optical properties of monolayer MoSe2 doped with C, O, Si, S, and Te atoms, respectively, under defective conditions are investigated based on first principles. It is found that the system is more structurally stable when defecting a single Se atom as compared to defecting a single Mo or two Se atoms. The electronic structure analysis of the system reveals that intrinsic MoSe2 is a direct bandgap semiconductor. The bandgap value of the system decreases with a single Se atom defect and introduces two new impurity energy levels in the conduction band. The defective systems doped with C and Si atoms all exhibit P-type doping. The total density of states of intrinsic MoSe2 is mainly contributed by the Mo-d and Se-p orbitals, and new density of state peaks appears near the conduction band after the defects of Se atoms. The total density of states of the defective system doped by each atom is mainly contributed by Mo-d, Se-p, and the result of the p orbital contribution of each dopant atom. By analyzing the dielectric function of each system, it is found that the intrinsic MoSe2 has the lowest static permittivity and the C-doped defect system has the highest static permittivity, which reaches 21.42. The C- and Si-doped defect systems are the first to start absorbing the light, and the intrinsic MoSe2 absorbs the light later, with its absorption edge starting at 1.25 eV. In the visible range, the reflection peaks of the systems move toward the high-energy region and the blue-shift phenomenon occurs. It is hoped that applying modification means to modulate the physical properties of the two-dimensional materials will provide some theoretical basis for broadening the application of monolayer MoSe2 in the field of optoelectronic devices. Methods: This study utilizes the first principle computational software package MS8.0 (Materials studio8.0) under density functional theory (DFT). The exchange–correlation potential (GGA-PBE) is described by the Perdew-Burke-Ernzerhof correlation function in CASTEP, and the potential function adopts the ultrasoft pseudopotential in the inverse space formulation. The plane wave truncation energy Ecut is set to 400 eV, the K-point is taken as 5 × 5 × 1, and the force convergence criterion is 0.05 eV/Å. The convergence accuracy of the total energy of the system is less than 1.0 × 10−5 eV/atom, the tolerance shift is less than 0.002 Å, and the stress deviation is less than 0.1 GPa. The vacuum layer is taken as 15 Å, which is intended to minimize the interlayer force. The vacuum layer was set to 15 Å to avoid the effect of layer-to-layer interaction forces in the crystal cell. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
24. First-principles study of the effect of doping on the optoelectronic properties of defective monolayers of MoSe2.
- Author
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Su, Dan, Liu, Guili, Ma, Mengting, Wei, Ran, Mu, Yansong, Yang, Zhonghua, and Zhang, Guoying
- Subjects
PSEUDOPOTENTIAL method ,ELECTRONIC structure ,DIELECTRIC function ,CONDUCTION bands ,DENSITY of states ,MONOMOLECULAR films ,DENSITY functional theory ,ELECTRO-optical effects - Abstract
Context: In this paper, the structural stability, electronic structure, and optical properties of monolayer MoSe
2 doped with C, O, Si, S, and Te atoms, respectively, under defective conditions are investigated based on first principles. It is found that the system is more structurally stable when defecting a single Se atom as compared to defecting a single Mo or two Se atoms. The electronic structure analysis of the system reveals that intrinsic MoSe2 is a direct bandgap semiconductor. The bandgap value of the system decreases with a single Se atom defect and introduces two new impurity energy levels in the conduction band. The defective systems doped with C and Si atoms all exhibit P-type doping. The total density of states of intrinsic MoSe2 is mainly contributed by the Mo-d and Se-p orbitals, and new density of state peaks appears near the conduction band after the defects of Se atoms. The total density of states of the defective system doped by each atom is mainly contributed by Mo-d, Se-p, and the result of the p orbital contribution of each dopant atom. By analyzing the dielectric function of each system, it is found that the intrinsic MoSe2 has the lowest static permittivity and the C-doped defect system has the highest static permittivity, which reaches 21.42. The C- and Si-doped defect systems are the first to start absorbing the light, and the intrinsic MoSe2 absorbs the light later, with its absorption edge starting at 1.25 eV. In the visible range, the reflection peaks of the systems move toward the high-energy region and the blue-shift phenomenon occurs. It is hoped that applying modification means to modulate the physical properties of the two-dimensional materials will provide some theoretical basis for broadening the application of monolayer MoSe2 in the field of optoelectronic devices. Methods: This study utilizes the first principle computational software package MS8.0 (Materials studio8.0) under density functional theory (DFT). The exchange–correlation potential (GGA-PBE) is described by the Perdew-Burke-Ernzerhof correlation function in CASTEP, and the potential function adopts the ultrasoft pseudopotential in the inverse space formulation. The plane wave truncation energy Ecut is set to 400 eV, the K-point is taken as 5 × 5 × 1, and the force convergence criterion is 0.05 eV/Å. The convergence accuracy of the total energy of the system is less than 1.0 × 10−5 eV/atom, the tolerance shift is less than 0.002 Å, and the stress deviation is less than 0.1 GPa. The vacuum layer is taken as 15 Å, which is intended to minimize the interlayer force. The vacuum layer was set to 15 Å to avoid the effect of layer-to-layer interaction forces in the crystal cell. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
25. MANAGEMENT AND PREVENTION OF ABUSES IN SPORTS.
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EUGEN, COSTIN DAN, CĂTĂLIN, POPESCU MARIUS, DANIEL, PĂSĂRIN LEONARDO, GABRIEL, POPA MARIAN, and LAURENȚIU, DIACONESCU DRAGOȘ
- Subjects
INTERNATIONAL competition ,SPORTS - Abstract
Sport has always played an important role in society, bringing joy, excitement and a sense of community as well as national pride. Over the centuries, sport has evolved from simple local competitions to global events watched by millions of people, gaining ever greater socio-political and economic importance. In the paper "Management and prevention of abuses in sports" we make a brief presentation of the types of abuses existing in sports and the solutions that can be used to eliminate these harmful actions, including a survey conducted on this topic. [ABSTRACT FROM AUTHOR]
- Published
- 2024
26. Effect of compressive strain on electronic and optical properties of Cr-doped monolayer WS2
- Author
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Mu, Yansong, Liu, Guili, Wei, Ran, and Zhang, Guoying
- Published
- 2024
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- View/download PDF
27. A review of oriented wurtzite-structure aluminum nitride films.
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Yang, Huiqian, Sun, Jing, Wang, Haijin, Li, Hao, and Yang, Bin
- Subjects
- *
ALUMINUM nitride films , *ALUMINUM nitride , *ACOUSTIC resonators , *PIEZOELECTRIC devices , *ACOUSTIC filters , *ZINC oxide thin films , *LEAD zirconate titanate - Abstract
Aluminum nitride (AlN), distinguished by exceptional mechanical, optical, and electronic properties, has found extensive applications in diverse domains, including heat dissipation substrates, information sensors, and acoustic filters. The surge in demand for compact and high-frequency mobile communications, particularly in the area of high-frequency film bulk acoustic resonators (FBARs), has driven the exploration of oriented wurtzite-structure AlN films. Nevertheless, the performance of FBARs is limited by the suboptimal piezoelectric coefficient and mechanical-coupling coefficient of AlN films. Here, this review presents recent progress in understanding the growth mechanisms of oriented wurtzite-structure AlN films and summarize existing strategies for manipulating crystalline orientations during the sputtering process. Additionally, this paper introduces chemical doping mechanisms and feasible approaches to enhance the piezoresponse of AlN films. By alloying Sc into AlN crystal lattice, the piezoelectric coefficient can be improved to a high level of ∼ 27.6 pC/N. Finally, the paper highlights the prospects of these AlN films in the field of on-chip piezoelectric devices and systems. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. First-principles study of the effect of doping on the optoelectronic properties of defective monolayers of MoSe2
- Author
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Su, Dan, Liu, Guili, Ma, Mengting, Wei, Ran, Mu, Yansong, Yang, Zhonghua, and Zhang, Guoying
- Published
- 2024
- Full Text
- View/download PDF
29. Adhesion, bonding and electronic properties of Ti/Zr doped c-BN(100)/Cu(100) interfaces: A first-principles study.
- Author
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Li, Hongzhe, Lu, Jinbin, Deng, Zihan, Miao, Qing, and Ma, Mingxing
- Subjects
- *
ELECTRONIC density of states , *ATOMIC structure , *BORON nitride , *COPPER-titanium alloys , *METALLIC glasses , *DENSITY of states , *METAL cutting - Abstract
Brazed monolayer cubic boron nitride (c-BN) tools are considered as promising tools for machining ductile metal materials. The interface between c-BN and filler alloys determines the properties of the tools to some extent. This paper uses first-principles calculations to study the atomic structures, work of adhesion, electronic properties, and density of states of c-BN(100)/Cu(100) clean and doped interfaces where the doping atoms are Ti/Zr. In this paper, four types of models are considered and calculated. The calculations reveal that Ti doping and Zr doping both increase the work of adhesion of the c-BN(100)/Cu(100) interface and the highest increase rate is 109 % and 83.4 %, respectively. The work of adhesion of c-BN(100)/Cu(100) interface doped with Ti is much higher than that doped with Zr and the electronic properties and density of states also prove this point of view. To sum up, Ti and Zr are both effective active elements to improve the performance of the c-BN/Cu interface, but, by comparison, Ti has better wettability to c-BN than Zr which provides an interpretation of the reported experimental results through the view of the atomic structures, work of adhesion, electronic properties and density of states. [Display omitted] • Four types of c-BN(100)/Cu(100) interface models were calculated using first-principles calculations. • The diffusion of Ti element at the c-BN/Cu interface is studied through the first-principles calculations. • The effect of adding Ti/Zr on enhancing the bonding strength and wettability of the interface were calculated. • Adding Zr alone is not as good as adding Ti. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. In situ electrodeposited Zn-doped CoNiS as an efficient and stable electrocatalyst for overall water splitting in neutral media.
- Author
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Li, Xuan, Yan, Wenjun, Fan, Binbin, and Wang, Zhongde
- Subjects
- *
HYDROGEN evolution reactions , *COBALT sulfide , *OXYGEN evolution reactions , *NICKEL sulfide , *GREEN fuels , *ZINC catalysts , *COBALT phosphide , *ON-chip charge pumps - Abstract
Zinc-doped cobalt nickel sulfides coupled with polypyrrole hollow nanospheres grown on carbon paper (Zn-CoNiS/PHS/CP) were developed by unipolar pulse electrodeposition (UPED) method as efficient and stable electrocatalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting in neutral media for the first time. With abundant active sites intrigued by moderate Zn doping, the optimized Zn 10 -CoNiS delivers improved catalytic performance with small overpotentials of 213 mV and 414 mV to achieve the current densities of 10 mA cm−2 for HER and OER respectively, and outstanding long-term stability. The water electrolyzer device with Zn 10 -CoNiS as both anode and cathode delivers a current density of 10 mA cm−2 at a cell voltage of 1.896 V in neutral media. The low charge transfer resistance of Zn-CoNiS and confinement effect of 2D Ni 9 S 8 /Co 9 S 8 nanosheets on 0D ZnS nanodots endow the bifunctional electrocatalysts with efficient activity and high stability, providing a competitive candidate for green hydrogen production. [Display omitted] • Unipolar pulse electrodeposition is used to construct cation-doped bimetallic sulfide. • Zn-CoNiS shows advanced catalytic activity and high stability for both HER and OER. • Doping of Zn optimizes electronic structure and enhances conductivity of Ni 9 S 8 /Co 9 S 8. • 0D/2D confinement effect promotes long-term stability of Zn-CoNiS in neutral media. • Zn 10 -CoNiS bifunctional catalyst delivers superb overall water splitting performance. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Biomass-derived carbon as a potential sustainable material for supercapacitor-based energy storage: Design, construction and application.
- Author
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Qiu, Bingbing, Hu, Wei, Zhang, Donghui, Wang, Yanfang, and Chu, Huaqiang
- Subjects
- *
CARBON-based materials , *ENERGY storage , *HYDROTHERMAL carbonization , *DOPING agents (Chemistry) , *WOOD , *SUPERCAPACITORS - Abstract
As an important energy storage device, supercapacitors have been widely used in the field of energy storage. Biomass becomes an ideal source of carbon electrode material for supercapacitors due to its low cost, wide source, and environmental friendliness. In this paper, a detailed summary of the various methods of preparation and activation of biomass-derived carbon electrode materials was presented. Meanwhile, the methods of doping atoms to improve the electrochemical properties of carbon electrode materials were systematically categorized. In addition, three methods to improve the performance of supercapacitors had been summarized, i.e., the addition of organic acids to the hydrothermal carbonization process, the addition of redox additives/redox electrolytes, and the intensification of wood biochar monoliths. Some of the major application areas of supercapacitors were summarized, as well as an outlook on the future direction of supercapacitor development. This review can provide some creative insights into the study of biomass-derived carbon as an electrode material for supercapacitors. [Display omitted] • Biochar is used as electrode material for supercapacitors due to its physicochemical properties. • The doping modification methods of biochar are reviewed. • Three measures to enhance the performance of supercapacitors have been extensively analyzed. • Based on the advantages of supercapacitors, the application status in major fields is summarized. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Conveyor CVD to high-quality and productivity of large-area graphene and its potentiality.
- Author
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Lee, Dong Yun, Nam, Jungtae, Lee, Gil Yong, Lee, Imbok, Jang, A-Rang, and Kim, Keun Soo
- Subjects
CHEMICAL vapor deposition ,X-ray photoelectron spectroscopy ,GAS detectors ,GAS absorption & adsorption ,MASS production - Abstract
The mass production of high-quality graphene is required for industrial application as a future electronic material. However, the chemical vapor deposition (CVD) systems previously studied for graphene production face bottlenecks in terms of quality, speed, and reproducibility. Herein, we report a novel conveyor CVD system that enables rapid graphene synthesis using liquid precursors. Pristine and nitrogen-doped graphene samples of a size comparable to a smartphone (15 cm × 5 cm) are successfully synthesized at temperatures of 900, 950, and 1000 °C using butane and pyridine, respectively. Raman spectroscopy allows optimization of the rapid-synthesis conditions to achieve uniformity and high quality. By conducting compositional analysis via X-ray photoelectron spectroscopy as well as electrical characterization, it is confirmed that graphene synthesis and nitrogen doping degree can be adjusted by varying the synthesis conditions. Testing the corresponding graphene samples as gas-sensor channels for NH
3 and NO2 and evaluating their response characteristics show that the gas sensors exhibit polar characteristics in terms of gas adsorption and desorption depending on the type of gas, with contrasting characteristics depending on the presence or absence of nitrogen doping; nitrogen-doped graphene exhibits superior gas-sensing sensitivity and response speed compared with pristine graphene. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
33. Ultra-fast photocatalytic degradation of Rhodamine B exploiting oleate-stabilized zinc oxide nanoparticles.
- Author
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Percivalle, Nicolò Maria, Carofiglio, Marco, Hernández, Simelys, and Cauda, Valentina
- Subjects
INDUSTRIAL wastes ,SEMICONDUCTOR doping ,MOIETIES (Chemistry) ,SEMICONDUCTOR design ,RHODAMINE B - Abstract
Rhodamine B (RhB) is a harmful dye released by industrial wastewaters, thus necessitating its urgent removal. Advanced oxidation processes constitute promising strategies to purify polluted water. Among others, photocatalysis relies on reactive oxygen species (ROS) produced by photocatalytic particles, typically semiconductors like titania or zinc oxide (ZnO), excited by solar or UV–Vis light. However, their wide band gap limits their catalytic capabilities within the absorption of the UV spectrum and causes fast electron–hole recombination. This study presents novel strategies to overcome these limitations: (i) doping semiconductors to increase photocatalytic efficiency; (ii) sensitization-mediated photocatalysis for visible light activation using chemical moieties to trap dye molecules; (iii) nanosizing the photocatalysts to enhance the surface area. ZnO nanoparticles, doped with iron or gadolinium and capped with oleic acid are here synthesized and tested in RhB dye solutions. Remarkably, the results demonstrate an ultra-fast RhB degradation, driven by oleic acid having crucial role in dye adsorption. The degradation mechanisms, including ROS-induced N-deethylation and xanthene group cleavage, are also unraveled. These findings underscore the efficacy of the proposed semiconductor photocatalyst design, highlighting a significant advancement with extensive potential applications in wastewater remediation. This innovative approach paves the way for more efficient and practical solutions to combat industrial dye pollution. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Effect of Y3+ and Co2+ co-doping on the structural, optical, magnetic and dielectric properties of LaFeO3 nanoparticles.
- Author
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Mishra, Debabrata, Nanda, Jyotirmayee, Parida, Sridhar, Sankaran, K. J., and Ghadei, Suryakanta
- Abstract
This study explores the comprehensive characterization of Y
3+ and Co2+ co-substituted LaFeO3 nanoparticles synthesized via the sol-gel auto-combustion method. The synthesized samples, La1-x Yx Fe1-y Coy O3 (x = 0,0.10 and y = 0,0.03,0.05,0.07) were characterized by employing various techniques such as x-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with EDX, Raman spectroscopy, UV-visible spectroscopy, and Vibrating Sample Magnetometry (VSM). The Raman and XRD analysis, supported by Rietveld refinement, provided conclusive evidence of a pure orthorhombic LaFeO3 phase. Microstructural studies unveiled an agglomerate-type, irregular particle distribution, while EDX analysis confirmed the elemental composition. The XPS study gives evidence about the presence of both Fe2+ and Fe3+ oxidation states, and Co has a Co3+ oxidation state. UV-vis spectroscopy demonstrated enhanced visible light absorption, revealing a reduced bandgap with increasing doping percentages. VSM measurements exhibited M-H loops, substantiating the weak ferromagnetic nature of the materials. Moreover, these nanoparticles exhibit dielectric constants and low dielectric losses, making them suitable for use in devices for communication. Overall, these findings may offer valuable contributions to the understanding of nanomaterial characteristics for potential applications in diverse fields. Research Highlights: Synthesis of La1-x Yx Fe1-y Coy O3 (x = 0,0.10 & y = 0,0.03,0.05,0.07) nanoparticles by sol-gel method. Confirmation of orthorhombic structure with Pbnm space group from XRD, Rietveld and Raman analysis with a decrease in crystallite size from 48 to 12 nm. Disclosement of the presence of both Fe2+ and Fe3+ oxidation states and Co doping has a Co2+ oxidation state from XPS analysis. The bandgap tuning from 2.09 to 1.56 eV with an increase in Co2+ doping concentrations. Weak ferromagnetic behavior observed for all the NPs. Enhanced Ms , Mr , and Hc for the 7% Co2+ doped LFO. The 7% Co2+ doped LFO exhibited the highest dielectric constant, lowest tangent loss and highest conductivity. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
35. Enhanced hydrogen evolution reaction activity through samarium-doped nickel phosphide (Ni2P) electrocatalyst.
- Author
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Shahroudi, Ali and Habibzadeh, Sajjad
- Subjects
NICKEL phosphide ,HYDROGEN evolution reactions ,SAMARIUM ,ELECTROCHEMICAL analysis ,HYDROGEN production ,CHARGE transfer ,ENERGY consumption - Abstract
Hydrogen evolution reaction (HER) stands out among conventional hydrogen production processes by featuring excellent advantages. However, the uncompetitive production cost due to the low energy efficiency has hindered its development, necessitating the introduction of cost-effective electrocatalysts. In this study, we introduced samarium doping as a high-potential approach to improve the electrocatalytic properties of nickel phosphide (Ni
2 P) for efficient HER. Samarium-doped Ni2 P was synthesized via a facile two-step vapor–solid reaction technique. Different physical and electrochemical analyses showed that samarium doping significantly improved pure Ni2 P characteristics, such as particle size, specific surface area, electrochemical hydrogen adsorption, intrinsic activity, electrochemical active surface area, and charge transfer ability in favor of HER. Namely, Ni2 P doped with 3%mol of samarium (Sm0.03 Ni2 P) with a Tafel slope of 67.8 mV/dec. and overpotential of 130.6 mV at a current density of 10 mA/cm2 in 1.0 M KOH solution exhibited a notable performance, suggesting Sm0.03 Ni2 P and samarium doping as a remarkable electrocatalyst and promising promoter for efficient HER process, respectively. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
36. In Vitro and In Vivo Human Metabolism of Ostarine, a Selective Androgen Receptor Modulator and Doping Agent.
- Author
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Taoussi, Omayema, Bambagiotti, Giulia, Gameli, Prince Sellase, Daziani, Gloria, Tavoletta, Francesco, Tini, Anastasio, Basile, Giuseppe, Lo Faro, Alfredo Fabrizio, and Carlier, Jeremy
- Subjects
DOPING agents (Chemistry) ,PROGESTERONE receptors ,TANDEM mass spectrometry ,METABOLISM ,ANDROGEN receptors ,HEPATOTOXICOLOGY ,MUSCLE growth - Abstract
Ostarine (enobasarm) is a selective androgen receptor modulator with great therapeutic potential. However, it is also used by athletes to promote muscle growth and enhance performances without the typical adverse effects of anabolic steroids. Ostarine popularity increased in recent years, and it is currently the most abused "other anabolic agent" (subclass S1.2. of the "anabolic agents" class S1) from the World Anti-Doping Agency's (WADA) prohibited list. Several cases of liver toxicity were recently reported in regular users. Detecting ostarine or markers of intake in biological matrices is essential to document ostarine use in doping. Therefore, we sought to investigate ostarine metabolism to identify optimal markers of consumption. The substance was incubated with human hepatocytes, and urine samples from six ostarine-positive cases were screened. Analyses were performed via liquid chromatography–high-resolution tandem mass spectrometry (LC-HRMS/MS) and software-assisted data mining, with in silico metabolite predictions. Ten metabolites were identified with hydroxylation, ether cleavage, dealkylation, O-glucuronidation, and/or sulfation. The production of cyanophenol-sulfate might participate in the mechanism of ostarine liver toxicity. We suggest ostarine-glucuronide (C
25 H22 O9 N3 F3 , diagnostic fragments at m/z 118, 185, and 269) and hydroxybenzonitrile-ostarine-glucuronide (C25 H22 O10 N3 F3 , diagnostic fragments at m/z 134, 185, and 269) in non-hydrolyzed urine and ostarine and hydroxybenzonitrile-ostarine (C19 H14 O4 N3 F3 , diagnostic fragments at m/z 134, 185, and 269) in hydrolyzed urine as markers to document ostarine intake in doping. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
37. The Difference between Plasmon Excitations in Chemically Heterogeneous Gold and Silver Atomic Clusters.
- Author
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Zeng, Fanjin, Long, Lin, Wang, Shuyi, Li, Xiong, Cai, Shaohong, and Li, Dongxiang
- Subjects
TIME-dependent density functional theory ,ATOMIC clusters ,SILVER clusters ,CHARGE exchange ,ELECTRONIC excitation - Abstract
Weak doping can broaden, shift, and quench plasmon peaks in nanoparticles, but the mechanistic intricacies of the diverse responses to doping remain unclear. In this study, we used the time-dependent density functional theory (TD-DFT) to compute the excitation properties of transition-metal Pd- or Pt-doped gold and silver atomic arrays and investigate the evolution characteristics and response mechanisms of their plasmon peaks. The results demonstrated that the Pd or Pt doping of the off-centered 10 × 2 atomic arrays broadened or shifted the plasmon peaks to varying degrees. In particular, for Pd-doped 10 × 2 Au atomic arrays, the broadened plasmon peak significantly blueshifted, whereas a slight red shift was observed for Pt-doped arrays. For the 10 × 2 Ag atomic arrays, Pd doping caused almost no shift in the plasmon peak, whereas Pt doping caused a substantial red shift in the broadened plasmon peak. The analysis revealed that the diversity in these doping responses was related to the energy positions of the d electrons in the gold and silver atomic clusters and the positions of the doping atomic orbitals in the energy bands. The introduction of doping atoms altered the symmetry and gap size of the occupied and unoccupied orbitals, so multiple modes of single-particle transitions were involved in the excitation. An electron transfer analysis indicated a close correlation between excitation energy and the electron transfer of doping atoms. Finally, the differences in the symmetrically centered 11 × 2 doped atomic array were discussed using electron transfer analysis to validate the reliability of this analytical method. These findings elucidate the microscopic mechanisms of the evolution of plasmon peaks in doped atomic clusters and provide new insights into the rational control and application of plasmons in low-dimensional nanostructures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Novel Sol-Gel Synthesis Route for Ce- and V-Doped Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 Piezoceramics.
- Author
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Marques, Larissa S., Weichelt, Michelle, Kuhfuß, Michel, Rambo, Carlos R., and Fey, Tobias
- Subjects
DIFFRACTION patterns ,CURIE temperature ,THERMAL stability ,THERMAL properties ,SPACE groups ,PIEZOELECTRIC ceramics ,LEAD-free ceramics - Abstract
To meet the current demand for lead-free piezoelectric ceramics, a novel sol-gel synthesis route is presented for the preparation of Ba
0.85 Ca0.15 Ti0.9 Zr0.1 O3 doped with cerium (Ce = 0, 0.01, and 0.02 mol%) and vanadium (V = 0, 0.3, and 0.4 mol%). X-ray diffraction patterns reveal the formation of a perovskite phase (space group P4mm) for all samples after calcination at 800 °C and sintering at 1250, 1350, and 1450 °C, where it is proposed that both dopants occupy the B site. Sintering studies show that V doping allows the sintering temperature to be reduced to at least 1250 °C. Undoped BCZT samples sintered at the same temperature show reduced functional properties compared to V-doped samples, i.e., d33 values increase by an order of magnitude with doping. The dissipation factor tan δ decreases with increasing sintering temperature for all doping concentrations, while the Curie temperature TC increases for all V-doped samples, reaching 120 °C for high-concentration co-doped samples. All results indicate that vanadium doping can facilitate the processing of BCZT at lower sintering temperatures without compromising performance while promoting thermal property stability. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
39. Potassium Iodide Doping for Vacancy Substitution and Dangling Bond Repair in InP Core-Shell Quantum Dots.
- Author
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Lee, Ji-Eun, Lee, Chang-Jin, Lee, Seung-Jae, Jeong, Ui-Hyun, and Park, Jea-Gun
- Subjects
QUANTUM dots ,POTASSIUM iodide ,RED light ,PASSIVATION ,ELECTRON paramagnetic resonance ,LIGHT filters ,LIGHT emitting diodes - Abstract
This work highlights the novel approach of incorporating potassium iodide (KI) doping during the synthesis of In
0.53 P0.47 core quantum dots (QDs) to significantly reduce the concentration of vacancies (i.e., In vacancies; VIn − ) within the bulk of the core QD and inhibit the formation of InPOx at the core QD–Zn0.6 Se0.4 shell interfaces. The photoluminescence quantum yield (PLQY) of ~97% and full width at half maximum (FWHM) of ~40 nm were achieved for In0.53 P0.47 /Zn0.6 Se0.4 /Zn0.6 Se0.1 S0.3 /Zn0.5 S0.5 core/multi-shell QDs emitting red light, which is essential for a quantum-dot organic light-emitting diode (QD-OLED) without red, green, and blue crosstalk. KI doping eliminated VIn − in the core QD bulk by forming K+ -VIn − substitutes and effectively inhibited the formation of InPO4 (H2 O)2 at the core QD–Zn0.6 Se0.4 shell interface through the passivation of phosphorus (P)-dangling bonds by P-I bonds. The elimination of vacancies in the core QD bulk was evidenced by the decreased relative intensity of non-radiative unpaired electrons, measured by electron spin resonance (ESR). Additionally, the inhibition of InPO4 (H2 O)2 formation at the core QD and shell interface was confirmed by the absence of the {210} X-ray diffraction (XRD) peak intensity for the core/multi-shell QDs. By finely tuning the doping concentration, the optimal level was achieved, ensuring maximum K-VIn − substitution, minimal K+ and I− interstitials, and maximum P-dangling bond passivation. This resulted in the smallest core QD diameter distribution and maximized optical properties. Consequently, the maximum PLQY (~97%) and minimum FWHM (~40 nm) were observed at 3% KI doping. Furthermore, the color gamut of a QD-OLED display using R-, G-, and B-QD functional color filters (i.e., ~131.1%@NTSC and ~98.2@Rec.2020) provided a nearly perfect color representation, where red-light-emitting KI-doped QDs were applied. [ABSTRACT FROM AUTHOR]- Published
- 2024
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40. Greatly Enhanced Thermoelectric Performance of Flexible Cu 2−x S Composite Film on Nylon by Se Doping.
- Author
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Zuo, Xinru, Han, Xiaowen, Wang, Zixing, Liu, Ying, Li, Jiajia, Zhang, Mingcheng, Huang, Changjun, and Cai, Kefeng
- Subjects
CARRIER density ,NYLON ,HYDROTHERMAL synthesis ,HOT pressing ,POWER density - Abstract
In this work, flexible Cu
2−x S films on nylon membranes are prepared by combining a simple hydrothermal synthesis and vacuum filtration followed by hot pressing. The films consist of Cu2 S and Cu1.96 S two phases with grain sizes from nano to submicron. Doping Se on the S site not only increases the Cu1.96 S content in the Cu2−x S to increase carrier concentration but also modifies electronic structure, thereby greatly improves the electrical properties of the Cu2−x S. Specifically, an optimal composite film with a nominal composition of Cu2−x S0.98 Se0.02 exhibits a high power factor of ~150.1 μW m−1 K−2 at 300 K, which increases by ~138% compared to that of the pristine Cu2−x S film. Meanwhile, the composite film shows outstanding flexibility (~97.2% of the original electrical conductivity is maintained after 1500 bending cycles with a bending radius of 4 mm). A four-leg flexible thermoelectric (TE) generator assembled with the optimal film generates a maximum power of 329.6 nW (corresponding power density of 1.70 W m−2 ) at a temperature difference of 31.1 K. This work provides a simple route to the preparation of high TE performance Cu2−x S-based films. [ABSTRACT FROM AUTHOR]- Published
- 2024
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41. Psychometric Properties of the Performance Enhancement Attitude Scale (PEAS) for Brazilian Sports.
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Codonhato, Renan, Aizava, Paulo Vitor Suto, Berbery, Enzo, and Fiorese, Lenamar
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PSYCHOMETRICS ,PERFORMANCE-enhancing drugs ,TEST validity ,ATTITUDE (Psychology) ,SPORTS - Abstract
Interest in psychosocial predictors of doping has been increasing as a way of finding new approaches to reduce the use of performance-enhancing drugs. This investigation aimed to test the psychometric properties of an instrument to assess doping attitudes in Brazilian athletes. The PEAS was validated in Brazilian sports through a process of translation, back-translation and content validity assessment, presenting satisfactory evidence based on its content (CVC > 0.80). Then, 994 athletes from different sexes, types of sports and competitive levels answered the Brazilian version of the PEAS. The results showed satisfactory evidence of validity based on its response process, internal structure (X
2 /df = 2.04; RMSEA = 0.032 (0.026–0.038); CFI = 0.96; TLI = 0.95) and reliability (Cronbach's α, McDonald's ω and CR > 0.70). Network analysis was also used to further explore the PEAS's internal structure. Overall, the results provide support for the adoption of the PEAS for Brazilian athletes and possibly other Portuguese-speaking countries. [ABSTRACT FROM AUTHOR]- Published
- 2024
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42. Morphology of the Surface of Silicon Doped with Lutetium
- Author
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Khodjakbar S. Daliev, Sharifa B. Utamuradova, Jonibek J. Khamdamov, and Zavkiddin E. Bahronkulov
- Subjects
silicon ,lutetium ,access ,doping ,defect ,diffusion ,oxygen ,carbon ,sem ,afm ,Physics ,QC1-999 - Abstract
In this paper, using a scanning electron microscope (SEM) and atomic analysis, the location map of microcomposites formed on the surface of n-Si, p-Si, n-Si and p-Si samples was studied. Force microscope (AFM) research devices. The atomic fractions of inclusions of carbon, oxygen and lutetium formed on the surface of the samples were studied. Also, using the ASM device, the sizes, relief and topographic appearance of defects formed on the surface of the samples were determined. In silicon samples doped with Lu, a decrease in the size of surface defects and the formation of nano-sized structures were found, which makes it possible to obtain materials with a more perfect crystal structure. Using a ZEISS GeminiSEM 300 scanning electron microscope, the structural structure, chemical composition and images of their arrangement of n-Si, p-Si, n-Si and p-Si samples were obtained. In this case, the electron accelerating voltage was 20 kV, and the pressure in the sample chamber was (10-3 mmHg). Research results show that the structural structure of micro- and nanocomposites formed in silicon mainly depends on the diffusion time and cooling rate of the samples after diffusion annealing.
- Published
- 2024
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43. Pb2+- and Sn2+-Doped (1-Phenylpiperazine)ZnBr4 Single Crystal with Highly Efficient Light Emission
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Cao, Yang, Zhang, Yong, Wei, Wei, Wang, Chen, Zhao, Xiaoyu, Chen, Xudan, and Lu, Zhenhao
- Published
- 2024
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44. Influence of Partial Substitution of Sn by Si on the Electrical, Mechanical, and Magnetic Properties of Ni44Mn44Sn12 Heusler Alloys
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Lima, Ariely V. B., da Silva, Debóra Moura, Mélo, Adelaide C., dos Passos, Tibério Andrade, Torquato, Ramon Alves, and de Oliveira, Danniel Ferreira
- Published
- 2024
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45. Unveiling Bi-functional potential of ZnMoO4-enriched nanoflakes modified electrodes for efficient photocatalysis and supercapacitors
- Author
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Ashraf, Sufyan, Sandhu, Zeshan Ali, Raza, Muhammad Asam, Bhalli, Ali Haider, Hamayun, Muhammad, Ashraf, Adnan, and Al-Sehemi, Abdullah G.
- Published
- 2024
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46. Effect of Y3+ and Co2+ co-doping on the structural, optical, magnetic and dielectric properties of LaFeO3 nanoparticles
- Author
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Mishra, Debabrata, Nanda, Jyotirmayee, Parida, Sridhar, Sankaran, K. J., and Ghadei, Suryakanta
- Published
- 2024
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47. Structural, Morphological, Optical and Magnetic Investigations of Mn-Doped BaTiO3 Nanostructures for Spintronic Applications
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Vinita, V. Sherlin, Jeyakumar, S. C., Kannan, P. S., Dhas, S. Sahaya Jude, Biju, C. S., Ahmed, K. Salman, and Almansour, Abdulrahman I.
- Published
- 2024
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48. Multifunctional Pr-V2O5/rGO hybrid nanomaterial for sensitive heavy metal ion detection and efficient photocatalytic dye degradation
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Harshitha, V., Kumar, K. S. Manjunatha, Nethravathi, P. C., Nagaraju, D. H., and Suresh, D.
- Published
- 2024
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49. Silicon Ion Implant Activation in β-(Al0.2Ga0.8)2O3
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Jacobs, Alan G., Spencer, Joseph A., Tadjer, Marko J., Feigelson, Boris N., Lamb, Abbey, Lee, Ming-Hsun, Peterson, Rebecca L., Alema, Fikadu, Osinsky, Andrei, Zhang, Yuhao, Hobart, Karl D., and Anderson, Travis J.
- Published
- 2024
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50. Thermoelectric properties of mechanically alloyed Cu3Sb1–y(Al/In)yS4 famatinites
- Author
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Yun, Sang and Kim, Il-Ho
- Published
- 2024
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- View/download PDF
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