Search

Based on density functional theory (DFT), a two-dimensional(2D) metal-organic framework (MOF) based on Co and Cu atoms were presented. Based on the phonon dispersion calculations, no imaginary mode is found in the phonon branches, which verifies that the crystal structures of MOF could be stable. Based on the calculation of electronic band structure, it is found that the Cu-based MOF is a metallic system by applying external electric field. While the Co-based MOF undergoes a transition from metal to semiconductor under external electric field. When the external electric field intensity reaches up to 0. 5 eV/Å, the band gap of Co-based MOF is around 0. 1 eV, while this does not happen in the Cu-based MOF. Furthermore, the N2 adsorption and the nitrogen reduction reaction (NRR) were investigated for the Co-based MOF, which shows that the NRR for the Co-based MOF exhibits good performance, and the electric field could enhance this effect of NRR. The free energy of NRR under external electric field of 0. 5 eV/Å is 0. 51 eV lower than that without electric field. Therefore, our study would prospectively guide the experimental researchers on the design of NRR. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Guangxi Normal University - Natural Science Edition is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

LiNbO3-MnTiO3 solid-solution single crystal doped with 10% and 20% MnTiO3 were synthesized by solid-state method at atmospheric pressure, and the structural characteristics of the samples were analyzed by X-ray diffractometer and spherical aberration corrected transmission electron microscope. The magnetoelectric properties and optical bandgap changes of the solid-solution single crystals were also studied. It was found that the MnTiO3 phase was homogeneously doped in the parent LiNbO3 phase and maintained the LiNbO3 - R3c structure. Due to the doping of MnTiO3, the sample exhibits weak magnetism at low temperature, which is derived from the high-spin state of Mn2+. Originated from the ferroelectric effect of the parent LiNbO3, the solid-solution exhibits obvious polarity. In addition, with the increase of MnTiO3, the optical band gap of the sample gradually decreases. [ABSTRACT FROM AUTHOR]

The effects of -F functional group on the structure, electronic properties and magnetic properties of Janus-type MXene 2D material CrVC were studied by first-principles of density functional theory. The calculation results indicate that the -F functional group changes the electronic properties and magnetic properties of CrVC. The nine possible structures of CrVCF2 exhibit ferromagnetic behavior, among which the structure of CrVCF2 -33 has the lowest energy and is the ground state, with a magnetic moment of 5. 01 μB and a band gap of 0. 099 eV, exhibiting semiconductor characteristics. The total magnetic moment of CrVCF2 -33 remains unchanged when - 4% - + 4% biaxial strain is applied; the energy increases with either compression or tension strain, but the change is less than 0. 2 eV; the band gap changes under the action of strain, when the tensile strain is 2. 4%, the band gap decreases to 0. 005 eV, which is close to zero. It can be considered a spin-zero band gap semiconductor. The results show that moderate strain can adjust the electronic structure of the CrVCF2 material, and it can even become a spin-zero band gap semiconductor, indicating its potential application value in the field of spintronics. [ABSTRACT FROM AUTHOR]

In recent years, semiconductor devices are developing towards high heat dissipation, high breakdown field strength and low energy consumption, so the ultra-wide band semiconductor material β-Ga2 O3 has a broad application prospect. However, effective doping is the basis for realizing β-Ga2 O3 devices. In this paper, Ga2O3/Al/Ga2O3/Al/Ga2O3 composite structure is experimentally prepared by magnetron sputtering, and the Al atoms are thermally diffused into the film by high-temperature annealing at the same time, so as to form Al-doped β-Ga2O3 thin film. Then, the laser zone melting method was used to melt and recrystallize the film area to further enhance the doping quality. The Al-doped β-Ga2O3 thin films were tested and characterized in terms of crystal properties, impurity content and optical properties. The experimental results show that: Al doping basically does not change the crystal structure of β-Ga2O3 thin films; the impurity content is gradually enhanced as the sputtering time of the Al layer becomes longer; in terms of the optical properties, the ultraviolet (UV) absorptivity of the films is 40% and 50% when the Al sputtering time is 5 and 10 s, and the UV absorption of the Al-doped β-Ga2O3 thin films is gradually enhanced with the increase of Al sputtering time; the light absorption of β-Ga2O3 thin film is close to 90% when the Al sputtering time is 300 s; and the low concentration of Al doping leads to the narrowing of the band gap width of β-Ga2O3 thin film. [ABSTRACT FROM AUTHOR]

The effects of -F functional group on the structure, electronic properties and magnetic properties of Janus-type MXene 2D material CrVC were studied by first-principles of density functional theory. The calculation results indicate that the -F functional group changes the electronic properties and magnetic properties of CrVC. The nine possible structures of CrVCF2 exhibit ferromagnetic behavior, among which the structure of CrVCF2 -33 has the lowest energy and is the ground state, with a magnetic moment of 5. 01 μB and a band gap of 0. 099 eV, exhibiting semiconductor characteristics. The total magnetic moment of CrVCF2 -33 remains unchanged when - 4% - + 4% biaxial strain is applied; the energy increases with either compression or tension strain, but the change is less than 0. 2 eV; the band gap changes under the action of strain, when the tensile strain is 2. 4%, the band gap decreases to 0. 005 eV, which is close to zero. It can be considered a spin-zero band gap semiconductor. The results show that moderate strain can adjust the electronic structure of the CrVCF2 material, and it can even become a spin-zero band gap semiconductor, indicating its potential application value in the field of spintronics. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Delafossite CuFeO2 is widely used in the field of photocatalysis due to its narrow band gap and easy availability, while the photogenerated carriers are easy to compound due to its centrosymmetric layered structure, limiting its photocatalytic effect. In view of this, this paper focuses on another configuration of, namely β-CuFeO2, which is an intrinsic ferroelectric semiconductor with phase stability, narrow band gap, and strong polarization. We construct the [011] surface with alternating arrangement of photogenerated electron and hole generation sites, which promotes charges separation under the action of ferroelectric built-in electric field to enhance the photocatalytic performance. Based on first-principles calculations, this study identified β-CuFeO2 as a direct bandgap semiconductor with thermodynamic stability, a C-type antiferromagnetism in the magnetic ground state, and the bandgap size of 1. 37 eV, with a theoretical ferroelectric polarization intensity of 83. 46 μC/cm², which is a good photocatalyst carrier. Further, using the surface oxygen precipitation reaction (OER) as a model, unpolarized direction surfaces [100], [010] and polarized direction surfaces [001], [011] were constructed to investigate the effect of ferroelectric polarization on the OER. The results show that the surface Valance Band Maximum (VBM) redox potential of β-CuFeO2 is mostly more than the water oxidation potential (1. 23 eV) and the polarized surface is easier to form. In addition, the [011] surface with fully exposed Cu-O atoms and alternating layers of Cu, Fe atoms in the polarization direction is the most susceptible to adsorption of water molecules and has the optimal OER catalytic activity. The electronic structure analysis of the rate-determining step for the OER on the [011] surface reveals that there are two electron pockets on the *O intermediate, and one electron pocket is consumed after the reaction to produce * OOH. This is the intrinsic mechanism of the OER rate-determining step on the polarization direction [011] surface. β-CuFeO2 ferroelectric semiconductor was constructed in this work and its basic properties were calculated by theoretical simulations, and different directions of surfaces were constructed to study the effect of ferroelectric polarization on the photocatalytic OER activity, which will provide a new perspective for the design of ferroelectric photocatalysts. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ceramics / Taoci Xuebao is the property of Journal of Ceramics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A CaMoO4 photocatalyst with high activity for degradation of aureomycin hydrochloride was prepared by sol-gel method. The phase structure, purity, functional group, surface morphology, optical properties and photocatalytic activity of the CaMoO4 photocatalyst were investigated by various characterization methods. The results showed that the CaMoO4 photocatalyst was tetragonal phase, and a small amount of C-O functional groups were present in the sample. The particles were approximately spherical, which consisted of large particles and fine particles. It had high visible-light response with an optical band gap value of 3.21 eV. The photocatalytic activity of CaMoO4 photocatalyst was studied at different drug concentrations, catalyst dosages and pH values using aureomycin hydrochloride as the target for degradation. The results showed that the degradation percentage reached 94% at the drug mass concentration of 200 mg/L, photocatalyst dosage of 1 g/L and pH of 7. The photocatalytic mechanism of the CaMoO4 photocatalyst was proposed based on experimental results and band theory. The mechanism study showed that the C-O functional groups provided extra energy for electron transition to the conduction band of the CaMoO4 photocatalyst and promoted the generation of electron hole pairs. Holes, hydroxyl radicals and superoxide radicals were the key factors to promote the degradation of aureomycin hydrochloride. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the wide band gap of pure wurtzite ZnO, most of the visible light was not be absorbed, four kinds of K-doped ZnO supercell models were constructed by using the first principles based on density functional theory, and four models are geometrically optimized, and then the energy band structure, density of states and light absorption performance of KXZn1-XO are calculated. The results show that the band gap of pure zinc oxide calculated by general gradient approximation (GGA)+U method is 3. 373 eV, which is consistent with the experimental value. With the increase of K doping concentration X, the band gap of ZnO firstly increases, then decreases and finally increases. The absorption edge band of KXZn1-XO shifts blue firstly and then red. [ABSTRACT FROM AUTHOR]

In this paper, a new GaSe/ZnS van der Waals heterostructure (vdWH) is devised and subjected to systematic analysis through first principles calculations in terms of its geometric, electronic and transport properties. The stability of GaSe/ZnS vdWH is verified through binding energy, phonon spectrum, and ab initio molecular dynamics (AIMD) simulation. Additionally, detailed calculations of plane average electron density difference and average electrostatic potential in the features of GaSe/ZnS vdWH interface are provided. The results show that GaSe/ ZnS vdWH comprises a heterostructure with a direct band gap of 2.19 eV and high carrier mobility. Among them, the electron mobility along the x direction reaches 1 394.63 cm²V-1⋅s-1, while the electron mobility along the y direction reaches 1 913.18 cm² ⋅V-1 ⋅s-1, demonstrating excellent performance and potential applications in electronic nano devices. [ABSTRACT FROM AUTHOR]

Using first-principles calculations, the different doping structures and electronic properties of Y atom on anatase TiO2 (101) surface were carefully studied to improve the photocatalytic activity of the surface. The results show that when Y atom is adsorbed on stoichiometric anatase TiO2 (101) surface, the most stable adsorption site is between two 3-fold coordinated oxygen atoms. Meanwhile, when Y atom on anatase TiO2 (101) surface with subsurface oxygen vacancy, the most stable adsorption site is between two 3-fold coordinated oxygen atoms that neighboring subsurface oxygen vacancy. In contrast, when Y atom on anatase TiO2 (101) surface with surface oxygen vacancy, the most stable adsorption site is on the top of 3-fold coordinated titanium that neighboring surface oxygen vacancy. The charge density results show that Y atom can be stably adsorbed on anatase TiO2 (101) surface. Furthermore, the density of states results show Y doped on the surface with surface oxygen vacancy can suppress the band gap from 1.67 eV to 1.44 eV, and induce extra impurity energy levels, which cause a fractional transition of electrons and improve surface photocatalytic ability. This study provides theoretical support for enhancing the surface photocatalytic ability of TiO2 (101) by single atom Y doping. [ABSTRACT FROM AUTHOR]

The mechanical property, electronic structure, and optical properties of tetragonal perovskite PbTiO3 and Ni, Cu, Zn-doped PbTiO3 were studied by first principles. The mechanical property calculations show that Ni-doped PbTiO3 exhibits the highest values for volume modulus, shear modulus, and elastic modulus among the three doping systems. Notably, the Nidoped system also has the highest Debye temperature. The G / B ratio represents the material's brittleness and toughness, which is highest for Zn-doped PbTiO3, indicating the highest degree of chemical bond orientation. The G / B range for Ni and Zn-doped systems is 0.56 < G / B <1.75, indicating brittle materials, while the intrinsic PbTiO3 and Cu-doped systems have G / B values less than 0.56, indicating ductile materials. The electronic structure reveals that the doped systems have narrower band gaps and reduced transition energies compared to the intrinsic system. The introduction of Ni introduces impurity levels at the Fermi energy level in PbTiO3, while Cu and Zn doping shifts the valence band maximum upwards, causing the Fermi level to enter the valence band and resulting in p-type conductivity for Cu and Zn-doped PbTiO3. The doping of Ni, Cu and Zn expands the absorption range of PbTiO3 to the infrared region and enhances the absorption intensity in the visible light range. Among the intrinsic PbTiO3 and three single-doped PbTiO3 materials, Cu-doped PbTiO3 exhibits the best photocatalytic properties. [ABSTRACT FROM AUTHOR]

The mechanical property, electronic structure, and optical properties of tetragonal perovskite PbTiO3 and Ni, Cu, Zn-doped PbTiO3 were studied by first principles. The mechanical property calculations show that Ni-doped PbTiO3 exhibits the highest values for volume modulus, shear modulus, and elastic modulus among the three doping systems. Notably, the Nidoped system also has the highest Debye temperature. The G / B ratio represents the material's brittleness and toughness, which is highest for Zn-doped PbTiO3, indicating the highest degree of chemical bond orientation. The G / B range for Ni and Zn-doped systems is 0.56 < G / B <1.75, indicating brittle materials, while the intrinsic PbTiO3 and Cu-doped systems have G / B values less than 0.56, indicating ductile materials. The electronic structure reveals that the doped systems have narrower band gaps and reduced transition energies compared to the intrinsic system. The introduction of Ni introduces impurity levels at the Fermi energy level in PbTiO3, while Cu and Zn doping shifts the valence band maximum upwards, causing the Fermi level to enter the valence band and resulting in p-type conductivity for Cu and Zn-doped PbTiO3. The doping of Ni, Cu and Zn expands the absorption range of PbTiO3 to the infrared region and enhances the absorption intensity in the visible light range. Among the intrinsic PbTiO3 and three single-doped PbTiO3 materials, Cu-doped PbTiO3 exhibits the best photocatalytic properties. [ABSTRACT FROM AUTHOR]

The latest research progress of ultrathin bismuth-based materials in the field of photocatalysis in recent years is reviewed, including pollutant degradation, photocatalytic hydrogen evolution, and reduction of carbon dioxide. As an innovative kind of semiconductor photocatalytic material, bismuth-based material is a kind of photocatalyst with moderate band gap, low cost, non-toxic and harmless. Its band gap adjust-ability and morphology adjustability provide the basic conditions for achieving good photocatalytic performance under ultrathin structure. The development of visible-light-responsive photocatalysts with two-dimensional layered structures has attracted extensive interest from scholars. Then, various bismuth-based photocatalytic materials that have been extensively studied are briefly introduced. The synthesis and modification methods of ultrathin bismuth-based photocatalysts are summarized, including sonication-assisted liquid exfoliation, ion intercalation-assisted liquid exfoliation, hydro/solvothermal synthesis, atomic layer deposition, etc. The problems existing in the preparation of ultrathin bismuth-based photocatalysts and the potential application value and development trend in the future are prospected. [ABSTRACT FROM AUTHOR]

BiOBr-based photocatalytic materials are potential photocatalytic materials, which have attracted extensive attention due to their unique narrow band gap, low cost, non-toxicity and higher structural stability, and show good application prospects in the field of wastewater treatment. In this review, the structure, preparation and mechanism of BiOBr-based photocatalytic materials as well as their applications in wastewater treatment are reviewed, and the challenges and prospects in the development and utilization of BiOBr-based photocatalytic materials a briefly discussed. [ABSTRACT FROM AUTHOR]

Diamond is a typical superhard multifunctional material with excellent properties such as the highest hardness, ultra-wide band gap and the highest thermal conductivity. The reserve of natural diamond is small and the price is expensive. Color diamonds are a very small part of nature diamonds and their coloring mechanisms are extremly complicated. It is a effective method to synthesize diamond by high temperature and high pressure method, but it is still a great challenge to modulate and realize color diamonds. In this paper, the quality, structural defects and impurities of color (pink and green) diamonds were studied by Raman, photuluminescence, infrared and visible absorption technologies, and the quality, defect changes with temperature and the cause of color were studied in detail. It is found that the coloring mechanism was related to electrically neutral N2 V defect (H3), shear stress, plastic deformation and NV0/NV- color center etc. Obtaining color diamonds by various methods is not only for their highly valued gemstones, but also helps people to further understand the formation mechanism of diamond, and provides a new reference for the cultivation of colored diamonds. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The microstructure of crystal materials plays a decisive role in macroscopic properties. An important fundamental direction in the synthesis of new materials is to investigate the relationship between electronic structure and optical properties. This study uses the first-principles based on density functional theory to systematically study the electronic structure and optical properties of X(PO3)2 (X = Zn, Cd, Hg), the three cationic ternary phosphate crystals containing d10 electron configuration. The band gap width of other three materials Zn(PO3)2, Cd(PO3)2, and Hg(PO3)2 gradually reduces, which are 5. 089, 4. 065 and 2. 942 eV, respectively. By analyzing the attribution of the band orbital near the band gap, it can be seen that the top of the valence band of X(PO3)2 is occupied by P atoms, O atoms and d orbitals of cations, while the bottom of the conduction band is mainly composed of P atoms, O atoms and occupied by the s, and p orbitals of cations. The charge density distribution maps of P and adjacent O atoms overlap significantly, which prove that P--O bonds have strong covalence. The static permittivities of X(PO3)2 are 3. 13, 2. 76, 3. 24, respectively. It can be calculated that the birefringence index of Zn(PO3)2 at 1 064 nm is 0. 032, the birefringence index of Cd(PO3)2 is 0. 025, and the birefringence index of Hg(PO3)2 is 0. 024. By calculating the birefringence magnitude of the compound and the anion group respectively, it is found that the birefringence is the result of the synergistic action of P--O group and cations. At the same time, the local analysis of the material is carried out, and the loss of electrons of the element is calculated, which further verify that the P--O group has strong covalence compared with Zn--O, Cd--O, and Hg--O. [ABSTRACT FROM AUTHOR]

Information on SF6 decomposition components can be detected using gas-sensitive sensor methods to assess the operational status of GIS equipment and detect the insulation defects early. Metal-doped SnP3 monolayer has good adsorption properties, which makes it promising for gas detection applications. Based on the first-principles, the parameters of adsorption energy, density of states, energy gap and desorption time of the system after the adsorption of SO2, H2 S, SOF2 and SO2 F2 by Pd-SnP3 monolayer were calculated and analyzed to explore the possibility of using this material for gas sensors. The results show that, in terms of adsorption performance, Pd-SnP3 monolayer only chemisorb SO2 F2. Combined with the results of density of states, differential charge density and transfer charge analysis, it is verified that the adsorption of SO2 F2 is significantly better than that of SO2, H2 S and SOF2. In terms of sensing characteristics, only the adsorption of SO2 F2 causes significant change in the energy gap of the system, and desorption of SO2 F2 from the Pd-SnP3 monolayer surface rapidly occur at temperature of 398 K and above. Therefore, the Pd-SnP3 monolayer has the potential to become a gas-sensitive material for the detection of SO2 F2 for its high selectivity and detectability to SO2 F2. This study provides a theoretical basis for the application of Pd-SnP3 monolayers in the field of gas-sensitive materials. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Molecular Science is the property of Journal of Molecular Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The photoelectric properties of four two-dimensional bilayer MoSSe/ WSSe van der Waals (vdW) heterostructures were investigated by the first-principles calculations. All four heterostructures have been conformed thermodynamic stable by the phonon spectra. Bilayer MoSSe/ WSSe heterostructures can be indirect or direct semiconductor, depending on the stacking routes. Moreover, two Janus MoSSe/ WSSe heterostructures show the suitable band gap of 1. 22 and 1. 88 eV, notable absorption index on the visible light, and band edge positions straddling the water redox potential. Therefore, Janus MoSSe/ WSSe heterostructures are expected to have application prospects in the field of photocatalytic water decomposition. [ABSTRACT FROM AUTHOR]

The crystal structure, charge density distribution, band structure, density of states (DOS), and optical properties of Al-doped β-Ga2O3 (i. e. (AlxGa1-x)2O3) with different Al concentrations were calculated by the first-principles based on density functional theory. The calculated results for intrinsic and Al-doped β-Ga2O3 with various Al concentrations were compared. The results show that, as the Al concentration increases, both the lattice parameters and bond lengths of (AlxGa1-x)2O3 monotonously decrease, whereas the band gap progressively widens. It is found that an intermediate band exists above the conduction band minimum (CBM), which is mainly composed of Ga 4s and Al 3p orbitals. Al doping enlarges the band gap by introducing impurity energy levels in this intermediate conduction band. Meanwhile, the introduction of Al atoms shifts the density of states to high-energy side by nearly 3 eV, which also leads to an increase of the band gap. According to the optical property calculation results, a significant blue shift for both the imaginary part of the dielectric function and the absorption coefficient are observed after Al doping. This blue shift behavior is generated by the transition from the O 2p states in the valence band maximum (VBM) to the Ga 4s states in the CBM. Moreover, the blue shift is intensified with the increase of Al doping concentration. This investigation can provide ideas and theoretical guidance for the construction of optoelectronic devices based on (AlxGa1-x)2O3. [ABSTRACT FROM AUTHOR]

In this paper, a series of ITO thin films with different concentrations of metal Sn doping were prepared by electron beam evaporation technique. X-ray diffractometer, atomic force microscope, UV-Vis-NIR spectrophotometer, four-probe resistivity meter and Z-scan system were used to measure and characterize the physical phase structure, microscopic morphology, optical absorption, square resistance and nonlinear optical properties of ITO films, respectively. The test results show that, with the increase of metal Sn doping concentration from 10% to 30%: the crystalline quality of the ITO film is enhanced; the surface roughness of the film increases and the grain size gradually increases; the plasma absorption is enhanced and the position of the absorption peak is red-shifted and the optical band gap is narrowed; the square resistance of the film continuously reduces; the nonlinear absorption coefficient gradually increases, and the maximum absolute value can be increased to 2.59 × 10-7 cm/ W. The finite-difference fitting results in the time domain show that the variation pattern of electric field intensity of ITO thin film samples with different metal Sn doping concentrations is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new two-dimensional phonon crystal structure was designed and studied deeply by finite element method and equivalent model method. It is found that the structure has good low-frequency sound absorption performance. Through theoretical derivation and simulation calculation, it is found that the structure has a complete four band gap within 0 ~ 800 Hz under the condition of lattice constant of 21 mm. The lower limit of the first band gap is as low as 40. 28 Hz, and the bandwidth is approximately 93 Hz. Sound transmission loss calculation shows that the structure has a good acoustic insulation effect in the low frequency domain, and the maximum sound insulation amount can reach 87. 31 dB. After analyzing the multiple vibration modes of the structure, the corresponding equivalent model is established, and the influence of different factors on the band gap is explored based on the equivalent model. The general regularities of the new two-dimensional phonon crystal are summarized. The results show that increasing the scatterer density and reducing the matrix density can increase the bandwidth, and increasing the filling rate and properly opening the scatterer can improve the band gap characteristics. The research may provide some ideas for solving low-frequency noise control problems in engineering application. [ABSTRACT FROM AUTHOR]

Studying the effect of biaxial strain on the electronic and optical properties of single-layer CdZnTe semiconductor materials provide theoretical support for the preparation of CdZnTe devices with excellent optical properties. In this paper, a single-layer CdZnTe model was built with the Material Studio software, and strain is applied to the model in the ( 100) and (010) directions. Based on the first-principle of density functional theory, the effects of biaxial strain on the band gap, effective mass of carrier, mobility and dielectric constant of single-layer CdZnTe were simulated and calculated. The results show that both tensile and compressive strains reduce the band gap of the single-layer CdZnTe, and biaxial strain effectively control the effective mass, mobility and dielectric constant of carriers. Compared with the tensile strain, compression strain of the same size has more obvious effect on the properties of the single-layer CdZnTe. With the increase of applied biaxial compression strain, the band gap of the single-layer CdZnTe gradually decreases, which leds to the increase of wavelength range of absorption light of the CdZnTe semiconductor, and the carrier effective mass and mobility of single-layer CdZnTe show an overall downward trend. Also, the increase of applied biaxial compression strain makes the real part of the dielectric constant gradually decrease and the imaginary part of the dielectric constant gradually increase, which enhances the metallicity of the single layer CdZnTe and improves its optical performance. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Jilin University (Science Edition) / Jilin Daxue Xuebao (Lixue Ban) is the property of Zhongguo Xue shu qi Kan (Guang Pan Ban) Dian zi Za zhi She and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the vibration problem of periodic lattices structure in the low-frequency field, based on the local resonance mechanism, a new composite two-dimensional periodic lattices structure was designed in this paper. The band gap mechanism of the structure and the band gap characteristics of low-frequency resonance were analyzed and studied by combining the finite element method. It is found that the initiation frequency of the band gap can be greatly reduced by optimizing the structure of the coating. The position of the band gap is determined by the natural frequency of the corresponding local resonance mode. The band gap can be adjusted to the range of meeting the practical engineering application by changing the material and size parameters of the structure. The numerical simulation results are consistent with the test results. The structure can open the full band gap of 50 Hz in the low frequency range from 40 Hz to 90 Hz, and the maximum vibration attenuation reaches 36 dB. This structure provides an effective method for obtaining low frequency and ultra-low frequency band gap of periodic lattices structure, and has potential application prospects. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Basic Sciences Journal of Textile Universities / Fangzhi Gaoxiao Jichu Kexue Xuebao is the property of Basic Sciences Journal of Textile Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

α-MoO3 is a typical layered semiconductor transition metal oxide, and its unique electronic structure and lattice structure have made it widely studied in recent years. Compared with bulk α-MoO3, α-MoO3 film has excellent optical, electrical and mechanical properties due to its two-dimensional geometric limitations. However, the epitaxial growth of singlelayer defect-free α-MoO3 film has not been realized so far. In this paper, molecular beam epitaxy was used in ultra-high vacuum, and a single-layer defect-free semiconductor α-MoO3 film was prepared by van der Waals epitaxial on highly oriented pyrolytic graphite (HOPG) for the first time, and linear defects were generated by hydrogen reduction. The microstructure and apparent energy gap of the defect-free single-layer film and the defect were studied by scanning tunneling microscope (STM). The results show that, high-quality single-layer α-MoO3 films can be prepared on HOPG substrates by accurately controlling the substrate temperature. The film thickness and cell size conform to the characteristics of single-layer α-MoO3, and the apparent energy gap of 1. 7 eV is determined by the scanning tunnel spectrum. The high quality of the grown film can be further confirmed by the moire pattern on the substrate HOPG. By introducing hydrogen, bright line defects perpendicular to the moire pattern can be obtained on the surface of the film, and the local apparent energy gap of the line defects is 0. 4 eV, that is, a narrowband semiconductor channel is realized inside a broadband semiconductor. [ABSTRACT FROM AUTHOR]

Nowadays, with the rapid development of electronic information technology, solar-blind ultraviolet (UV) detectors having large anti-interference ability and higher sensitivity are attracting much attention. Possessing ultra-wide band gap, high optical absorption coefficient, good thermal conductivity, and high breakdown field strength, hexagonal boron nitride (h-BN) has become a promising material for solar-blind UV detectors. Additionally, high mechanical strength and optical transparency of h-BN make it a potential candidate for flexible detector. However, the h-BN films prepared at low temperatures often contain many defects, which greatly limit their performance as a detector. In this work, high-quality h-BN films were prepared on sapphire and Si substrates using B as growth source at room temperature by reactive magnetron sputtering method, and then a high-performance solar-blind UV detector was fabricated based on h-BN films. The prepared h-BN solar-blind UV detector has extremely low dark current (0. 07 pA), high responsivity (1. 37 μA/ W) and detectivity (2. 73 × 10 10 Jones) at 3 V. These results indicate that preparation of high-quality h-BN film and its solar-blind UV detector at room temperature are feasible. The study also provides a reference for the application of h-BN detector working at room temperature. [ABSTRACT FROM AUTHOR]

Diamond has excellent material properties such as wide band gap (5. 47 eV), high carrier mobility (3 800 cm 2 / (V·s) for holes and 4 500 cm 2 / (V·s) for electrons), high thermal conductivity (22 W·cm - 1·K - 1 ), high critical breakdown field strength ( > 10 MV/ cm), and optimal Baliga’ s figure of merit, which make diamond semiconductor devices ideal choices for the applications in extreme conditions such as high temperature, high frequency, high power, and strong irradiation. With the breakthroughs in diamond crystal growth by CVD techniques and p-type doping of diamond crystal, research on Schottky barrier diode ( SBD) based on boron-doped diamond has been widely carried out. In this review, the working principles of the diamond SBD are introduced in detail. The growth processes of highly doped p-type thick films, ptype films of low doping drift region are investigated, and the conditions for the formation of ohmic contact and Schottky contact between different metals and diamond crystals are studied. Then the preparation processes of transverse, vertical and pseudovertical device structures and their effect on forward, reverse and breakdown characteristics of the SBDs are analyzed. The modulation of the internal electric field of SBDs by device structures like field plate, passivation layer and edge terminal, which strengthens the reverse breakdown voltage of the device, is illustrated. Finally, the application prospects and challenges of diamond SBDs are summarized. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Jilin University (Science Edition) / Jilin Daxue Xuebao (Lixue Ban) is the property of Zhongguo Xue shu qi Kan (Guang Pan Ban) Dian zi Za zhi She and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Photonic crystals (PCs) are a kind of nanostructure with periodically varying refraction rates, which contain photonic band gaps that can regulate the propagation of light. PCs show beautiful structural colors if the band gaps occur in the visible light band. Due to their unique optical features, PCs have a wide range of applications, such as those in photoelectric material, chemical sensors, and ink-free printing. We introduced the frontier scientific field to the undergraduates. Using the improved Stöber method, we synthesized diameter-controllable monodisperse silica nanoparticles. As a simple and rapid method to obtain a thin layer, drop-coating is innovatively used here to assemble PCs. This experiment can be completed in 4 h. The method is inexpensive, and it helps students understand significant phenomena with interest. As a result, students can consolidate their experimental skills and learn nano-chemistry and colloidal self-assembly. The experiment is related to structural chemistry and optics theories. By integrating these theories, students can understand how structural colors are generated. [ABSTRACT FROM AUTHOR]

In this paper, the electronic and piezoelectric properties of two-dimensional Janus CrXY (X/ Y = S, Se,Te) systems were investigated. The results show that the Janus CrXY systems are excellent semiconductor materials and the band gap widths of Janus CrXY range from 0. 27 eV to 0. 83 eV. The strain regulation in the x-axis direction has a great influence on the band gap, while the strain regulation in the z-axis direction has little influence on the band gap, indicating that the electronic properties of the system have good stability in the z-axis direction. The piezoelectric properties of the system were studied by density generalized perturbation method, the results show that all three materials have large out-of-plane piezoelectric coefficients d33, especially, the d33 of CrSeTe reaches 56. 89 pm/ V, which is about ten times that of the common piezoelectric material AlN (d33 = 5. 60 pm/ V). This research provides theoretical support for the practical application of two-dimensional Janus CrXY systems in the field of flexible and intelligent nanomaterials. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Science & Engineering (1673-2812) is the property of Journal of Materials Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)