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Our investigation focused on an in-depth examination of the physical properties of KZnH3 and NaZnH3, with lattice parameters of 4.04 and 3.72 Å, respectively. Both compounds exist stably in a cubic structure and exhibit metallic behavior with no band gap. At the Fermi level, the total and partial densities of states exhibit a significant conductivity, confirming the metallic behavior. These materials have brittle and anisotropic properties. Because of their greater bulk modulus, average shear modulus, and Young's modulus, NaZnH3 appears harder compared to KZnH3. Optical properties indicate significant absorption and optical conductivity in the energy spectrum of 6–9 eV. NaZnH3 has a greater static refractive index and reflectivity as compared to KZnH3. The research on hydrogen storage suggests that both of these materials can store hydrogen, however, NaZnH3 is a more promising candidate due to its higher hydrogen storage capability. [ABSTRACT FROM AUTHOR]

Effect of functional on structural, elastic, optoelectronic and thermoelectric characteristics of semiconducting MgX2Se4 (X = Lu, Y) spinels has been realized by WIEN2k code. The lattice constant of MgY2Se4 is slightly greater than that of MgLu2Se4, and these quantities are slightly deviated from the experimental values, where the error does not exceed 1.3%. The cohesive energy proves that both spinels are chemically stable in the normal case, and this stability is more pronounced in MgLu2Y4. The large ionic radius of Lu compared to Y explains the high bulk modulus of MgY2Se4 as well as its hardness. The spinels under study have Г → Г direct band gap located between 1.178 and 1.4 eV for all the functionals, proving their semiconductor nature. Se-s, Y-d, Lu-d states in MgY2Se4 and MgLu2Se4 dominate the upper valence band, while the first conduction band located between Fermi level and 1.5 eV is empty. There is a strong coupling between Se-p–Lu-p sites for MgLu2Se4 and Se-p–Y-p states in MgY2Se4, which reflects their hybridization. The high absorption in the ultraviolet range, the band gap between 1 and 2.4 eV and the refractive index in the range of 2.29–2.61 favour these spinels as absorbers in solar cells. Peaks of all the optical quantities studied relating to the mBJ–GGA functional are shifted to the right compared with GGA and GGA+SO approximations. The thermoelectric parameters were investigated as a function of photon energy and temperature using GGA+SO functional. [ABSTRACT FROM AUTHOR]

This manuscript reports the computational study of three new perovskite-type hydrides for solid-state hydrogen storage technology. Herein, Density Functional Theory (DFT) has been implemented within CASTEP code to probe the structural, electronic, mechanical, optical and hydrogen storage properties of MgXH 3 (X = Al, Sc and Zr). Thermodynamic stability assessments reveal that all materials exhibit negative formation energy (Δ E f), guaranteeing their energetic stability and suitability for experimental synthesis. Band structure and density of states plots highlight metallic properties in MgXH 3 hydrides. The mechanical stability of these perovskites was ensured by the compliance of their elastic constants with Born's stability criteria. Bulk modulus, shear modulus, Poisson's ratio, Cauchy pressure, etc. are also processed from elastic constants. Pugh coefficient and Cauchy pressure unveil ductile behavior in MgAlH 3 and MgZrH 3 , and brittleness in MgScH 3. Optical properties revealed that MgXH 3 compounds have maximum absorption and conductivity in the ultraviolet region. The gravimetric hydrogen storage capacities were theoretically determined as 5.274, 4.015, and 2.487 wt%, for MgAlH 3 , MgScH 3 , and MgZrH 3 respectively. This research work suggests that MgXH 3 (X = Al, Sc and Zr) can be used as promising materials for hydrogen storage applications. • Three novel perovskite hydrides are examined for hydrogen storage using DFT. • MgXH 3 (X = Al, Sc and Zr) hydrides are mechanically and thermodynamically stable. • MgXH 3 perovskites are metallic in nature. [ABSTRACT FROM AUTHOR]

The present work reports a comparative study on CuO and 3.0% Mn-doped CuO nanofibers (NFs) produced by the electrospinning method. State-of-the-art characterization techniques such as Electron Energy Loss Spectroscopy (EELS) and X-Ray photoelectron Spectroscopy (XPS) have been employed to determine the multivalent states and elucidate their electronic structure at the Cu-L3,2 (2p) edge. The CASTEP code has been used to model CuO (P1) and Mn-doped (C 2/c) with the GGA-PBE functional on the supercomputing system with the Xeon10 module (10 nuclei). Structural characterization was done by using a CM 200 Philips Transmission Electron Microscope (TEM) and the chemical state of surfaces with ESCALAB 250Xi XPS Thermoscientific TM. The NFs present an indirect energy bandgap, Eg = 2.03 eV and 2.85 eV, respectively. The results show that the Cu-L3,2 edge presents degenerate states associated with Cu 2p - O and Cu 3d - O hybridization, indicated as Cu3+.

Structural, elastic, mechanical and electronic properties of pure and zinc-doped SrTiO3 at the concentration in the range (1–10%) are studied by first-principles calculations. The structural parameters of synthesized compounds agree well with the standard data depicting the growth of stable compounds. A slight obvious increase in the lattice constant of 3.9245 Å is observed in Zn-doped SrTiO3 due to the deviation of the atomic radii of Zn and Ti. Elastic constants and mechanical parameters of SrTiO3 are closer to their available theoretical and experimental data. The investigated compounds exhibit brittle behavior for all Zn ratios. The doping zinc concentration reduces the indirect band gap value. The doping concentration 2%, gives a band gap value closer to the experimental one. The band gap of pure SrTiO3 is 1.827 eV and after doping with Zn for concentration from 1% to 10%, the optimized values are 1.970, 1.886, 1.802, 1.718, 1.635, 1.552, 1.470, 1.389, 1.310, 1.231 and 1.154 eV. [ABSTRACT FROM AUTHOR]

This work presents a Density Functional Theory (DFT) study of the single perovskite CsXH 3 (X = Co, Zn). We used the CASTEP code to perform first-principles calculations and investigate the hydrogen storage properties of CsXH 3 (X = Co, Zn). We calculated the structural, Hydrogen, mechanical, electronic, optical, and thermal properties of CsXH 3 (X = Co, Zn) perovskite materials for hydrogen storage applications. Electronic properties reveal that CsXH 3 (X = Co, Zn) has a metallic behavior. The calculated value of formation energy is −0.47 eV/atom and −0.18 eV/atom for CsCoH 3 and CsZnH 3 , respectively, which means that the studied materials are synthesizable and thermodynamically stable. Our results show that CsXH 3 (X = Co, Zn) is a promising material for hydrogen storage, as it exhibits high hydrogen storage capacity. The gravimetric ratio values are 2.82 wt% and 3.09 wt% for CsCoH 3 and CsZnH 3 , respectively. The determined elastic constants show that CsXH 3 (X = Co, Zn) is mechanically stable. Our study provides valuable insights into using single perovskite CsXH 3 (X = Co, Zn) as a potential material for hydrogen storage applications. • Performance of DFT study for CsXH 3 (X = Co, Zn) perovskites materials for hydrogen storage applications. • The elastic constants values show that CsXH 3 (X = Co, Zn) is mechanically stable. • Calculated formation energy is −0.47 and −0.18 for CsCoH 3 and CsZnH 3 respectively. • The studied materials are synthesizable, thermodynamically stable and are most suitable for hydrogen storage applications. [ABSTRACT FROM AUTHOR]

Thiamine hydrochloride (THCL), also known as vitamin B1, is an active pharmaceutical ingredient (API), present on the list of essential medicines developed by the WHO, which proves its importance for public health. THCL is highly hygroscopic and can occur in the form of hydrates with varying degrees of hydration, depending on the air humidity. Although experimental characterization of the THCL hydrates has been described in the literature, the questions raised in previously published works suggest that additional research and in-depth analysis of THCL dehydration behavior are still needed. Therefore, the main aim of this study was to characterize, by means of quantum chemical calculations, the behavior of thiamine hydrates and explain the previously obtained results, including changes in the NMR spectra, at the molecular level. To achieve this goal, a series of DFT (CASTEP) and DFTB (DFTB+) calculations under periodic boundary conditions have been performed, including molecular dynamics simulations and GIPAW NMR calculations. The obtained results explain the differences in the relative stability of the studied forms and changes in the spectra observed for the samples of various degrees of hydration. This work highlights the application of periodic DFT calculations in the analysis of various solid forms of APIs. [ABSTRACT FROM AUTHOR]

The aim of this study is to comprehensively examine the structural composition and properties of the AgAlS2 crystal during its high-pressure phase. This analysis delves into the second coordination environment of the crystal structure and elucidates the distinct transformations it undergoes during the phase transition. The band energy structure was calculated, and the origin of electronic levels was clarified. It is shown that the crystal becomes non-stratified during the phase transition. This study also determined the values of the crystal's carrier effective masses, underscoring its spatial anisotropy. It was found that the calculated optical functions are similar to the crystal in the chalcopyrite structure, and their differences are shown. Further, this study involved the calculation of the crystal's phonon spectrum, revealing the spectrum's transformation during the phase transition. The vibrational frequencies were also obtained, with a symmetrical classification of vibrational modes. Finally, this study derived the infrared and Raman spectra of the AgAlS2 crystal, thereby providing a comprehensive picture of the crystal during its high-pressure phase. [ABSTRACT FROM AUTHOR]

The optimized structure of Pd3M2Se2 (M = Pb and Sn) compounds is used to explore the M‐Site cation variation. Density functional theory (DFT) using generalized gradient approximation (GGA) with Hubbard potential (GGA+U) and Wu and Cohen (GGA+WC) functionals are used to examine the physical characteristics. The chemical stability is indicated by negative values for the formation energy and obtained as −26.75 eV and −28.25 eV for Pd3Pb2Se2 and Pd3Sn2Se2 compounds respectively. The feeble interaction of Se‐4p and Pb‐6p orbital electrons in the conduction band results in a considerable contribution. As a result, the energy bands of the Pd3Pb2Se2 structure are altered in such a way that it has a high electrical conductivity. The Pd3Pb2Se2 and Pd3Sn2Se2 structures are metallic, with both ionic and covalent interactions, according to electronic population studies. While the extinction coefficient for the Pd3Pb2Se2 compound is 4.20 at 0.65 eV, the Pd3Sn2Se2 structure has a highest peak of 7.20 at this energy, indicating their photoelectric applicability. The Pd3Pb2Se2 and Pd3Sn2Se2 structures seemed to be transparent to photons energy at 16.4 eV and 18.20 eV respectively. These shandite compounds showed superior absorption for Ultraviolet (UV) photon energy as well as efficient infrared and visible light absorption with conductivity. [ABSTRACT FROM AUTHOR]

The purpose of this research is to investigate the structural, electronic, and optical properties of ZnX compounds, particularly those with X = Te, S, and O, which have direct bandgaps that make them optically active. To gain a better understanding of these compounds and their related properties, we conducted detailed calculations using density functional theory (DFT) and the CASTEP program, which uses the generalized gradient approximation (GGA) to estimate the cross-correlation function. Our results for lattice modulus, energy bandgap, and optical parameters are consistent with both experimental data and theoretical predictions. The energy bandgap for all compounds is relatively large due to an increase in s-states in the valence band. Our findings suggest that the optical transition between (O - S - Te) - p states in the highest valence band and (Zn - S - O) - s states in the lowest conduction band is shifted to the lower energy band. Therefore, ZnX compounds (X = Te, S and O) are a promising option for optoelectronic device applications, such as solar cell materials.

In our study, we create peanut-shaped boron nitride nanotubes by introducing Stone–Wales defects and applying uniaxial tensile strain. We carefully examine the structural and electronic properties by systematically applying different strain levels along the nanotubes' axial direction, both before and after introducing the defects. Our results reveal that Stone–Wales defects have a notable impact on the bond lengths and bond angles within the nanotubes. Furthermore, we conduct a detailed analysis of the band structures for both pristine nanotubes and those with Stone–Wales defects under varying strain conditions. Our findings demonstrate a clear correlation between the changes in the band structures and the density of state diagrams. Importantly, the introduction of Stone–Wales defects induces the appearance of new energy states within the band gap, leading to a significant reduction in the band gap size. Through our calculations, we provide clear evidence that the electronic properties of the nanotubes are distinctly affected by the presence of Stone–Wales defects and the application of tensile strain. [ABSTRACT FROM AUTHOR]

This study uses the CASTEP code and the density functional theory (DFT) to look into the structure, electrical properties, and optical properties of MgO. The generalised gradient approximation (GGA-PW91 approximation) was used to measure both the energy of the band gap and the energy of the exchange-correlation. This computation was done based on the cubic MgO crystal structure, which has a space group of Fm-3m and a 3x3x3 supercell. In structural optimization, the results that are expected for the lattice constant and the bulk modulus elastic constant are very close to known experiments and theories. The anticipated direct band gap of 4.283eV at the G point is in excellent agreement with the results of the tests. Also, the total (DOS) and partial (PDOS) densities of states have been measured, and the results of the absorption coefficient have been looked at in terms of the different energies of the phonons that hit the material. [ABSTRACT FROM AUTHOR]

MgAl2O4 spinel matrix nanocomposite with TiC, AlTi3, and Al2O3 was directly fabricated using the mechanical alloying (MA) method with Mg, TiO2, Al, and graphite as the starting powder mixture. This methodology was used to synthesize magnesium aluminate spinel (MSA) matrix nanocomposite with having the advantage of no subsequent heat treatment. The mixture of the powders was milled at room temperature using a high-energy planetary ball mill with a vial rotation speed of 400 rpm in the air. The phases and morphological analysis after the MA process were characterized by X-ray diffraction and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). Followed by 20 h of ball-milling, all the desired phases of MgAl2O4, TiC, AlTi3, and Al2O3 appeared in XRD results, and also a small fraction of raw materials remained. The major reactions to synthesize MgAl2O4/TiC-AlTi3-Al2O3 spinel matrix nanocomposite were the reduction of TiO2 by Al and Mg. [ABSTRACT FROM AUTHOR]

The aim of this study is to comprehensively examine the structural composition and properties of the AgAlS2 crystal during its high-pressure phase. This analysis delves into the second coordination environment of the crystal structure and elucidates the distinct transformations it undergoes during the phase transition. The band energy structure was calculated, and the origin of electronic levels was clarified. It is shown that the crystal becomes non-stratified during the phase transition. This study also determined the values of the crystal’s carrier effective masses, underscoring its spatial anisotropy. It was found that the calculated optical functions are similar to the crystal in the chalcopyrite structure, and their differences are shown. Further, this study involved the calculation of the crystal’s phonon spectrum, revealing the spectrum’s transformation during the phase transition. The vibrational frequencies were also obtained, with a symmetrical classification of vibrational modes. Finally, this study derived the infrared and Raman spectra of the AgAlS2 crystal, thereby providing a comprehensive picture of the crystal during its high-pressure phase.

Thiamine hydrochloride (THCL), also known as vitamin B1, is an active pharmaceutical ingredient (API), present on the list of essential medicines developed by the WHO, which proves its importance for public health. THCL is highly hygroscopic and can occur in the form of hydrates with varying degrees of hydration, depending on the air humidity. Although experimental characterization of the THCL hydrates has been described in the literature, the questions raised in previously published works suggest that additional research and in-depth analysis of THCL dehydration behavior are still needed. Therefore, the main aim of this study was to characterize, by means of quantum chemical calculations, the behavior of thiamine hydrates and explain the previously obtained results, including changes in the NMR spectra, at the molecular level. To achieve this goal, a series of DFT (CASTEP) and DFTB (DFTB+) calculations under periodic boundary conditions have been performed, including molecular dynamics simulations and GIPAW NMR calculations. The obtained results explain the differences in the relative stability of the studied forms and changes in the spectra observed for the samples of various degrees of hydration. This work highlights the application of periodic DFT calculations in the analysis of various solid forms of APIs.

In this paper, cobalt concentration on the interface mechanism between diamond coating and cemented carbide substrate was used by first-principles calculation and experimental study. The interface model was built and analyzed. The effect of pretreatment time on the Co concentration on the surface of cemented carbide was studied. The relationship between the bond strength of the WC–Co/diamond interface was analyzed based on energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), Raman spectroscopy and indentation. The simulation results showed that the bonding strength of the WC–Co/diamond interface increased gradually with the decrease of Co concentration and has an extreme value. The test results showed that the pretreatment decobaltization time was 20 min and the bonding strength of the membrane substrate is good. What was more, the results of EDX, SEM, Raman, indentation confirmed this conclusion. [ABSTRACT FROM AUTHOR]

In this work, the structure, phase composition, hardness and tensile strength of the AlMgB14-based material obtained by spark plasma sintering (SPS) were investigated. According to the XRD results, the spark plasma sintered material contains 94 wt% AlMgB14 phase and 6 wt% spinel MgAl2O4. Analysis of the SEM images showed that the obtained AlMgB14 sample has a dense structure; the relative density of the sample is 98.6%. The average microhardness of the spark plasma sintered (SPSed) sample is 29 ± 0.88 GPa. According to the results of the Brazilian test, the tensile strength of AlMgB14 is 56 MPa. The fracture is characterized by a single straight tensile crack that divides the sample along the compression line into two halves. The type of fracture in the AlMgB14 sample can be characterized as a cleavage fracture due to crack growth occurring in accordance with the transcrystalline fracture. The tensile strength of the obtained material is in good agreement with the tensile strength of boride and oxide ceramics studied in other works. [ABSTRACT FROM AUTHOR]

Resumen: En este trabajo se presenta un estudio en el que se aplica la teoría funcional de densidad (DFT), utilizando el software CASTEP, para cristales de silicato (K2SiO3, K2Si2O5 y K2Si4O9) y de óxido de silicio (cuarzo). La densidad de estados (DOS) de estos silicatos muestra que los dos tipos de átomos de oxígeno, puente (BO) y no puente (NBO), tienen una distribución electrónica significativamente diferente en los orbitales 2p y 2s, debido a un ambiente químico inmediato diferente. Esto lleva a un desplazamiento a energías menores de las bandas de valencia s y p de la densidad de estados parcial (PDOS) del NBO de alrededor de 2 eV respecto de la PDOS del BO. En el cristal de menor contenido en K2O (K2Si4O9), se incrementan los enlaces covalentes Si-O debido a la transferencia de carga electrónica del orbital 4s del átomo de potasio al NBO, y de este NBO al átomo de silicio y, finalmente, a todos los átomos del tetraedro, lo que permite mejorar la fuerza de enlace del sistema. Este hecho resulta en que el material final tenga una mayor resistencia mecánica. Por otro lado, en el K2Si2O5 (el cual posee un NBO por tetraedro) el enlace Si-O es más débil con respecto al del K2Si4O9, tendencia que se acentúa en el K2SiO3 (que posee dos NBO por tetraedro). Esta misma tendencia sigue la dureza Vickers calculada teóricamente. Este estudio se ha aplicado a vidrios de silicato de potasio obtenidos experimentalmente y se han comparado varias propiedades mecánicas con las teóricas de los respectivos cristales de igual composición química. Los NBO tanto de cristales como de vidrios se han cuantificado a partir de las unidades estructurales Qn. Se ha observado que las propiedades mecánicas de los vidrios no pueden ser explicadas únicamente por las contribuciones de los tetraedros libres unidos por el vértice y caracterizados por sus BO y NBO como función de la concentración en K2O, es decir por los Qn. Esto es debido a que la DFT de CASTEP para sistemas cristalinos considera todo orden de interacción. Por ello es necesario utilizar estructuras a alcance intermedio, denominadas como unidades estructurales rígidas (RSU). La contribución de los tetraedros libres se ha calculado usando la dureza Vickers del cristal y un factor de apantallamiento por la pérdida de la interacción de medio y largo alcance. En el trabajo se explica el comportamiento de la dureza Vickers y módulo de Young de vidrios de SiO2-K2O en un amplio rango de composiciones molares. Summary: In this work, a study is presented in which the density functional theory (DFT) is applied, using the CASTEP software, for crystals of silicate (K2SiO3, K2Si2O5 and K2Si4O9) and of silicon oxide (quartz). The Density of State (DOS) of these silicates shows that the two types of oxygen atoms, bridging (BO) and non-bridging (NBO), have a significantly different electron distribution in the 2p and 2s orbitals, due to a different and close chemical environment. This leads to a displacement to lower energies (around 2 eV) of the s and p valence bands of the partial density state (PDOS) of the NBO regarding the PDOS of the BO. In the crystal with the lowest K2O concentration (K2Si4O9), the covalent Si-O bonds are increased due to the electronic charge transfer of the 4s orbital from the potassium atom to the NBO, and from this NBO to the silicon atom and, finally, to all the atoms of the tetrahedron, which allows to improve the bond strength of the whole system. This fact results in the final material having a higher mechanical resistance. On the other hand, in K2Si2O5 (which has one NBO per tetrahedron) the Si-O bond is weaker compared to K2Si4O9, a tendency that is highlighted in K2SiO3 (which has two NBOs per tetrahedron). This same trend follows the theoretically calculated Vickers hardness. This study has been applied to experimentally obtained potassium silicate glasses and several mechanical properties have been compared with the theoretical properties of the respective crystals of similar chemical composition. The NBO of both crystals and glasses have been quantified from the Qn structural units. It has been observed that the glass mechanical properties cannot be only explained by the contributions of the free tetrahedral joined by the vertice and characterized by their BO and NBO as a function of the concentration in K2O, that is by Qn. This is because CASTEP's DFT theory for crystalline systems considers every order of interaction. Therefore, it is necessary to use intermediate-range structures called rigid structural units (RSUs). The contribution of free tetrahedral has been calculated using the Vickers hardness of the crystal and a screening factor for the loss of medium and long range interactions. This work explains the behaviour of the Vickers hardness and Young's modulus of SiO2-K2O glasses in a wide range of molar compositions.

Two-dimensional perovskite materials have recently attracted significant interest in solar cell applications. This study employed DFT calculations to investigate the structural, electronic, optical, magnetic, thermal properties and spectroscopic limited maximum efficiency (SLME) of Cs 3 Sb 2 X 9 (X = Cl, Br) perovskites. The dynamic vibrational stability was calculated using the phonon energy dispersion curve; results show that Cs 3 Sb 2 X 9 (X = Cl, Br) is dynamically stable. The electronic band structure revealed that these materials exhibit semiconductor behavior with energy bandgaps of 2.41 eV and 1.77 eV for Cs 3 Sb 2 Cl 9 and Cs 3 Sb 2 Br 9 , respectively. The Cs 3 Sb 2 Br 9 shows higher absorption and conductivity at comparatively lower frequencies of absorbed light. Furthermore, the magnetic characteristics of the investigated compounds demonstrate that there are no net magnetic moments. The thermodynamic properties analysis indicated a strong correlation between heat capacity and temperature. We have used SLME analysis to determine the theoretical power conversion efficiency for Cs 3 Sb 2 X 9 (X = Cl, Br) perovskites. The determined results of SLME show that Cs 3 Sb 2 Cl 9 and Cs 3 Sb 2 Br 9 exhibit SLME values of 12.63 % and 26.40 %, respectively, at 298.15 K, suggesting that both compounds can be used in solar cells. [ABSTRACT FROM AUTHOR]

• This is the report on overall analyses of Bi and Cu-based 9 DP compounds by replacing the A-site with Cs, Rb, and K atoms, and the X-site with I, Br, and Cl atoms in the A 2 BiCuX 6 structure. • The A-site cationic replacement has put not much impact on the E g as well as the DOS of all 9 compounds. But the Cu-3 d and X- p orbitals are the major contributors of VBM whereas Bi-6 p orbital is the major contributor of CBM. • From the optical properties study, it is confirmed that the most suitable candidate Cs 2 BiCuI 6 DP compound has a ε 2 ω of 8.98, α(ω) of 0.68 × 105 cm−1, n(ω) of 3.4, σ(ω) of 2.24 1/fs, R(ω) of 0.34 and loss function of 2.71, respectively in the visible spectrum. • A comparative study between inorganic Cs 2 BiCuI 6 based FTO/WS 2 /Cs 2 BiCuI 6 /MXene/Pt structured and hybrid organic–inorganic ion ((FA) 2 BiCuI 6) based FTO/WS 2 /(FA) 2 BiCuI 6 /MXene/Pt structured PV cell has been performed using SCAPS-1D software. The Cs 2 BiCuI 6 based one provides an optimum PCE of 30.11 % as compared to (FA) 2 BiCuI 6 based one (20.21 %). • For better optimization of the device parameters, the effect of variation in thickness, defect density, carrier mobility, temperature, R S , and R Sh of the device are performed. Thus, it has been achieved a maximum PCE of 31.25 %, FF of 82.71 %, V OC of 1.24 V and J SC of 30.40 mA/cm2 for absorber thickness of 600 nm, ETL thickness of 130 nm, HTL thickness of 300 nm, N t of 1013 cm−3 for absorber, ETL and HTL each, charge carrier mobility of 20 cm2V−1s−1, temperature of 300 K, R S of 0.5 Ω-cm2 and a R Sh of 106 Ω-cm2, respectively. Presently, the Bi-based 3D A 2 (BB′)X 6 double perovskites (DPs) show an excellent photovoltaic (PV) performance with ambient stability compared to Pb-based counterparts. The structural, electronic, and optical properties analyses of A 2 BiCuX 6 (A=Cs, Rb, K, X=I, Br, Cl) DPs are performed by CASTEP software, and the Cs 2 BiCuI 6 is found to be the best suitable absorber among all of them. The density of states calculation reveals that Cu-3 d and X- p orbitals are the major contributors to valence band maxima (VBM), whereas Bi-6 p orbitals are responsible for the contribution to conduction band minima (CBM). Using SCAPS-1D simulation tool, the impact of variation in thickness, defect density, mobility of charge carriers, series resistance (R S), shunt resistance (R Sh), and device temperature on PV performance of the device has been analysed. The optimised all inorganic FTO/WS 2 /Cs 2 BiCuI 6 /MXene/Pt structured device has provided an excellent PV performance i.e., PCE of 31.25 %, FF of 82.71 %, V OC of 1.24 V, and J SC of 30.40 mA/cm2 using 2D structured ETL (WS 2) and HTL (MXene). This analysis provides an advanced understanding of cheap, environmentally stable, easily obtainable Bi-Cu based DP counterparts, which can be used in the fabrication of PV cells practically. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT study of lead-free X 2 NaIO 6 double-Perovskite. • X 2 NaIO 6 are narrow bandgap semiconductor materials. • They absorb light more strongly in the visible region. • Both of these compounds are mechanically stable, anisotropic, and brittle. • X 2 NaIO 6 are potential candidate for optoelectronic and solar cell applications. The standard lead-free double perovskite X 2 NaIO 6 has become a viable alternative for lead-based perovskites due to its remarkable optoelectronic capabilities, high stability, non-toxicity, and multifunctionality. This study is presented to evaluate the structural, electronic, optical, and mechanical properties of X 2 NaIO 6 (X=Sr, Ba) by applying a first-principles method based on density functional theory (DFT). These investigations were carried out at the level of the generalized gradient approximation (GGA) for the exchange–correlation functional, parameterized by Perdew Burke and Erenzerhof (PBE) within the CASTEP code. The tolerance factors (τ) for Sr 2 NaIO 6 and Ba 2 NaIO 6 are 0.98 and 1.0, confirming the cubic nature of both compounds. Both compounds Sr 2 NaIO 6 and Ba 2 NaIO 6 have direct narrow bandgap values of 1.57 eV and 1.42 eV, respectively. We also presented a comprehensive study of their optical properties. Shear modulus (G), Poisson's ratio (v), elastic coefficient (C ij), anisotropy (A), bulk moduli (B), Young's modulus (Y), and Pugh's ratio (B/G) are computed. The combined electronic, optical, and mechanical investigations show that both materials are suitable for optoelectronic, photovoltaic, and solar cell applications. [ABSTRACT FROM AUTHOR]

The effect of Cl content on total energies of W-Cl system. [Display omitted] • The monoclinic WCl 5 and the trigonal WCl 3 are the more stable phases. • WCl 6 phase may be present in two crystal forms, such as the hexagonal (P -3 m1, 164) β-WCl 6 and the hexagonal (R -3, 148) α-WCl 6. • The obtained bond distance in α-WCl 6 and β-WCl 6 are significantly longer than the mean bond distances in WCl 4 and WCl 5. • Direct Γ-Γ band gap for WCl 3 (1.78 eV), WCl 5 (0.08 eV), β-WCl 6 (1.746 eV) and α-WCl 6 (1.803 eV), while WCl 4 has the metallic character. • The atomic geometry of monoclinic WCl 4 and WCl 5 contain an ordered arrangement of W vacancies. • The PDOS profile of W and Cl are similar throughout the whole energy region, indicating the presence of hybridization between W and Cl electrons. • One shares the charge density at each point between atoms in proportion to the free atomic density, so that the distribution of bound and localized atoms resembles the molecular density. The molecular structures of WCl 6 , WCl 5 , WCl 4 , WCl 3 have been optimized by density functional theory calculations. We report the stability of the phases in the ground state, the total energies and the optoelectronic properties of the W-Cl system. We find that the material having a low tungsten concentration shows a low DOS at the Fermi level, which implies a high resistivity. Both polymorphs of WCl 6 are crystalline solids at room temperature and show the (α- WCl 6) and (β- WCl 6) phases of space group R -3 and P -3 m1 observed at 228 °C. The change in temperature influences the structural, electronic and optical properties. The object of this paper does not concern only the study of all phases, but also one controls the physical states of the molecular materials when they are subjected to polymorphic changes. Calculations on the molecular structure under symmetry indicated an orbitally degenerate ground state with bond distances in good agreement with experiment. [ABSTRACT FROM AUTHOR]

In situ X-ray crystallography powder diffraction studies on beta silicon carbide (3C-SiC) in the temperature range 25–800 °C at the maximum peak (111) are reported. At 25 °C, it was found that the lattice parameter is 4.596 Å, and coefficient thermal expansion (CTE) is 2.4 × 10 − 6 /°C. The coefficient of thermal expansion along a-direction was established to follow a second order polynomial relationship with temperature (α 11 = − 1.423 × 10 − 12 T 2 + 4.973 × 10 − 9 T + 2.269 × 10 − 6 ). CASTEP codes were utilized to calculate the phonon frequency of 3C-SiC at various pressures using density function theory. Using the Gruneisen formalism, the computational coefficient of thermal expansion was found to be 2.2 × 10 − 6 /°C. The novelty of this work lies in the adoption of two-step thermal expansion determination for 3C-SiC using both experimental and computational techniques. [ABSTRACT FROM AUTHOR]

Based on the first-principles calculations of density functional theory (DFT), the crystal structure, molecular structure, electronic properties, and optical absorption properties of methyl urotropine perchlorate under hydrostatic compression in the range of 0 ~ 100 GPa were calculated. The results show that the crystal structure of methyl urotropine perchlorate undergoes two structural transformations under hydrostatic compression. The H1A-H1B bond breaks at 25 GPa, generating two new covalent bonds N3-H1A and O1-H1B. The covalent bonds of O2A-C1 and Cl1-H3A are formed at 85 GPa. The compression ratio of lattice constants (a, b, c) and unit cell volume change abruptly at 25 GPa and 85 GPa, respectively. The conclusion that new bonds are formed under high pressure is further demonstrated by analyzing the partial density of states (PDOS) of N3, H1A, O1, H1B, O2A, C1, Cl1, and H3A atoms. The absorption spectrum showed that the absorption peak of methyl urotropine perchlorate gradually enhanced with the increase of pressure and the highest absorption peak shifted to high frequency. Highlights: The structure of methyl urotropine perchlorate was optimized, and its lattice constants (a, b, c, and V) and compression ratios at different pressures were calculated. Methyl urotropine perchlorate undergoes two structural transitions at pressurization to 25 GPa and 85 GPa, with the breaking of old bonds and the formation of new bonds. The DOS of methyl urotropine perchlorate was analyzed, further confirming the structural transformation by high pressure. The effect of high pressure on optical absorption properties was investigated. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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.)

We studied the structural, elastic, electronic, dynamic and optical properties of scandium and yttrium nitrides in the zinc blend structure. The GGA, LDA and GGA-PBESOL approaches, as well as the HSE hybrid functional, were used in the representation of the electronic exchange and correlation effects. The lattice constant, the bulk modulus and its pressure derivative calculated in the HSE hybrid approach are predictions. The elastic constants and B/G ratio infer that ScN and YN are elastically stable and ductile in nature. ScN and YN in the zinc blend structure show an isotropic linear compressibility and anisotropic Young's modulus, shear modulus and Poisson's ratio. The anisotropy and hardness in ScN and YN compounds are more pronounced in the LDA approach. The X–X (W–W) direct band gap in scandium (yttrium) nitride translates its semiconductor character in the zinc blend structure. The N: p orbit and small contribution of Sc: d (Y: d) site are responsible to the optical modes, while Sc: d (Y: d) site and small contribution of N: p orbit are the sign of acoustical modes. The absorption peaks are assigned to photo transitions energies from maximum valence band to minimum conduction band.

Tin monochalcogenides (SnSe, SnS), with advantages of earth abundance, environmental friendly, chemical stability, and less toxicity can be used in Li-ion batteries, piezoelectric, optoelectronics, sensors, and thermoelectric. Here, we used the ultra-soft pseudo-potential technique depending on density functional theory with generalized gradient approximation (GGA) to calculate the electronic, optical, and structural properties by changes related to the reduction of dimensionality from bulk to monolayer or bilayer structure. The calculated parameters show that the bandgap energies of SnS and SnSe semiconductors (0.5∼1.25 eV) cover the broadband range, and their static dielectric constant confirms the isotropic nature. We compare our theoretical results of different approximations with previously reported DFT-based and experimental results. The calculations of tin monochalcogenides show that as thickness increases, isotropic behavior increases, and material becomes crystalline. This method opens a new window to deeply understand monochalcogenide's structural, optical, and electronic properties for numerous applications, like thermoelectric, photovoltaic, and energy storage devices.

First-principles calculations were used to estimate the anisotropic elastic and thermal properties of Ti2lnX (X = C, N) and Zr2lnX (X = C, N) M2AX phases. The crystals' elastic properties were computed using the Voigt-Reuss-Hill approximation. Firstly, the material's elastic anisotropy was explored, and its mechanical stability was assessed. According to the findings, Ti2lnC, Ti2lnN, Zr2lnC, and Zr2lnN are all brittle materials. Secondly, the elasticity of Ti2lnX (X = C, N) and Zr2lnX (X = C, N) M2AX phase are anisotropic, and the elasticity of Ti2lnX (X = C, N) and Zr2lnX (X = C, N) systems are different; the order of anisotropy is Ti2lnN > Ti2lnC, Zr2lnN > Zr2lnC. Finally, the elastic constants and moduli were used to determine the Debye temperature and sound velocity. Ti2lnC has the maximum Debye temperature and sound velocity, and Zr2lnN had the lowest Debye temperature and sound velocity. At the same time, Ti2lnC had the highest thermal conductivity. [ABSTRACT FROM AUTHOR]

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) 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.)

Titanium dioxide (TiO2) is one of the highly promising energy materials. Nevertheless, it has a wide energy bandgap that restricts its absorption capacity within the visible light spectrum. To investigate the effects of doping the transition-metal Palladium (Pd) into anatase TiO2, we perform first-principles calculations in the framework of density functional theory (DFT). All calculations are carried out in the scheme of Hubbard potential (U) correction to account for the correlated effects in TiO2. For this purpose, the first-principles calculations are carried out with the CASTEP code in the formalism of GGA + U. The Pd-doped TiO2 was examined in detail for its electronic structure, lattice parameters, E-K representation, the density of states and optical properties. The results showed that lattice parameters of TiO2 changed after doping. The band structure, partial density of state (PDOS), total density of state (TDOS), complex dielectric function, refractive index, optical absorption, and energy loss function of Pd-doped anatase are improved drastically. It was observed that the doping process adds Pd 4d electronic states into different energy ranges and thus reduces middle states within the band gap region. Our electronic structure calculations indicate augmentation of d-states around the Fermi level, induced by doping Pd. Additionally, compared with the undoped TiO2, the absorption edges of Pd-doped TiO2 show a shift from the UV spectrum towards the visible light region. The results indicate that the GGA + U approach is unique in determining the real band structure of semiconductors which is close enough to empirical results.

In this study lattice parameters, band structure, and optical characteristics of pure and V-doped ZnO are examined by employing (USP) and (GGA) with the assistance of First-principles calculation (FPC) derived from (DFT). The measurements are performed in the supercell geometry that were optimized. GGA+U, the geometrical structures of all models, are utilized to compute the amount of energy after optimizing all parameters in the models. The volume of the doped system grows as the content of the dopant V is increased. Pure and V-doped ZnO are investigated for band structure and energy bandgaps using the Monkhorst–Pack scheme's k-point sampling techniques in the Brillouin zone (G-A-H-K-G-M-L-H). In the presence of high V content, the bandgap energy decreases from 3.331 to 2.043 eV as seen by the band diagram. PDOS diagram was utilized to get the insight of the electronic structure of the atoms and the amount to which all energy bands contribute to a particular orbit of the atoms. As the V content grew, so did the PDOS for all of the states. The manipulation of bandgaps was carried out in a way that narrowing the bandgaps occurs, resulting in a redshift of the absorption spectrum in the IR region. At lower photon energies, the imaginary and real parts dielectric functions have increased. The effectiveness of V atoms on transmissivity especially in the low energy region of the V-doped ZnO perovskite has been verified compared to the other theoretical results.

The density function theory (DFT) with GGA and PBE was employed to determine the structural, electrical, and optical characteristics of pure and Cu doped AgZnF 3 type Fluro-perovskite. The structural properties of composite are calculated in realistic agreement with those testified in the literature. The band gap of the hybrid AgZnF 3 is small and indirect. AgZnF 3 contained a calculated band width of 1.52 eV. AgZnF 3 's total electronic properties were principally controlled by the Zn atom, whereas the Zn-d state and the F-p state had a minor impact on its partial electronic properties and state density. Cu doping modified AgZnF 3 's electrical band structure by narrowing the band gap. With increasing doping concentrations, the partial densities of states, which are likewise impacted by doping concentrations decreased. This material is appropriate for a variety of applications due to the improvement in optical characteristics and decrease in the band gap. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phonon and structural stability of Cs 2 SiBr 6 Cs 2 GeBr 6 and Cs 2 SnBr 6 perovskites. • Determined band energy gaps to be favorable for photovoltaic applications. • Mechanical and thermodynamic stability, reliability and compatibility for photovoltaic devices. • IR and Raman active phonon modes in the range 0–400 cm−1 for Cs 2 SiBr 6 Cs 2 GeBr 6 and Cs 2 SnBr 6 perovskites. Exploring prospective materials for energy storage and production is one of the largest confrontation of the century. Solar optoelectronic energy is one of the utmost exceptional renewable resources now a days, due to their small Environmental impact and wide availability. The perovskite type double halides are promising materials for optoelectronic and solar applications. In this article, the optoelectronic characteristics of newly perovskite double halides Cs 2 SiBr 6 Cs 2 GeBr 6 and Cs 2 SnBr 6 are addressed. The calculated band gaps 2.70 eV (Cs 2 SiBr 6), 1.80 eV (Cs 2 GeBr 6), 2.90 eV (Cs 2 SnBr 6) with raising performance for optoelectronic applications. The optical properties are explored by large dielectric constants, high optical absorption coefficients, small optical loss etc. Moreover, the mechanical properties for the studied materials have been performed to confirm the mechanical stability, comactability and reliability of the materials for photovoltaic applications. The thermodynamic and vibrational stability and compatibility has been verified due to negative values of enthalpy, cohesive energies and no soft phonon mode of vibrations. These optoelectronic energy related calculations confirmed that the perovskites type double halides may Cs 2 SiBr 6 , Cs 2 GeBr 6 and Cs 2 SnBr 6 may be novel, stimulating potential materials and can be synthesized experimentally for next generation photovoltaic devices and related applications. [ABSTRACT FROM AUTHOR]

Cellulose acetate(CA)/graphene oxide (GO) composites have been widely used in the drug development and biosensing due to its excellent biocompatibility and strength. It is important to study their adsorption mechanisms for the application of CA/GO in detail. Here, the interaction between GO and CA was described by DFT simulations, and CA/GO composite films were characterised using tensile testing and FTIR spectroscopy. DFT calculations indicated that there is no chemical bonding between CA and GO adsorption but hydrogen bonding from hydroxyl groups facilitates the adsorption process. FTIR of CA/GO results show that the characteristic peaks of hydroxyl groups in the composite film is shifted towards high frequencies compared to the pure CA film, which is a strong evidence of hydrogen bonding of hydroxyl groups during the adsorption process. The tensile test results indicate that hydrogen bonds contribute to the tensile strength and elastic modulus of the CA/GO composite film. [ABSTRACT FROM AUTHOR]

In this study, LaAlO3 doped with Sr/Co/Mn was prepared by sol‐gel method, with its infrared (IR) radiative properties and variation mechanism investigated by X‐ray powder diffraction, X‐ray photoelectron spectroscopy, IR, scanning electron microscopy. Meanwhile, the electronic band structure was simulated by Cambridge Serial Total Energy Package. The conclusions are as follows: the order of emissivity in the near‐IR band is La0.67Sr0.33Al0.67Mn0.33O3> La0.67Sr0.33Al0.67Co0.33O3> LaAl0.67Mn0.33O3> LaAl0.67Co0.33O3> LaAlO3. In 0–2.5 μm at room temperature, the emissivity of La0.67Sr0.33Al0.67Mn0.33O3 can reach 0.9504. The emissivity increase mechanism lies in the further free carrier absorption caused by numerous small polarons formed by the Sr‐Mn co‐doping and increased concentration of electron‐oxygen vacancies. Meanwhile, the Sr‐Mn co‐doping causes lattice distortion and strengthens the lattice vibration absorption. The band gap of La0.67Sr0.33Al0.67Mn0.33O3 is 0.910 eV, much smaller than 3.445 eV of LaAlO3, favorable to the valence band electron transition, generating more electron‐oxygen vacancy pairs and promoting free carrier absorption. La0.67Sr0.33Al0.67Mn0.33O3 conduction band migrates to the lower energy region, while Mn3d impurity energy level appears. Thanks to the band gap reduction, dielectric function imaginary peaks, and absorption coefficient peaks are red‐shifted. Due to its high emissivity, La0.67Sr0.33Al0.67Mn0.33O3 has a high utilization value and broad potential application. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Physics is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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 this study, LaAlO3 doped with Sr/Co/Mn was prepared by sol‐gel method, with its infrared (IR) radiative properties and variation mechanism investigated by X‐ray powder diffraction, X‐ray photoelectron spectroscopy, IR, scanning electron microscopy. Meanwhile, the electronic band structure was simulated by Cambridge Serial Total Energy Package. The conclusions are as follows: the order of emissivity in the near‐IR band is La0.67Sr0.33Al0.67Mn0.33O3> La0.67Sr0.33Al0.67Co0.33O3> LaAl0.67Mn0.33O3> LaAl0.67Co0.33O3> LaAlO3. In 0–2.5 μm at room temperature, the emissivity of La0.67Sr0.33Al0.67Mn0.33O3 can reach 0.9504. The emissivity increase mechanism lies in the further free carrier absorption caused by numerous small polarons formed by the Sr‐Mn co‐doping and increased concentration of electron‐oxygen vacancies. Meanwhile, the Sr‐Mn co‐doping causes lattice distortion and strengthens the lattice vibration absorption. The band gap of La0.67Sr0.33Al0.67Mn0.33O3 is 0.910 eV, much smaller than 3.445 eV of LaAlO3, favorable to the valence band electron transition, generating more electron‐oxygen vacancy pairs and promoting free carrier absorption. La0.67Sr0.33Al0.67Mn0.33O3 conduction band migrates to the lower energy region, while Mn3d impurity energy level appears. Thanks to the band gap reduction, dielectric function imaginary peaks, and absorption coefficient peaks are red‐shifted. Due to its high emissivity, La0.67Sr0.33Al0.67Mn0.33O3 has a high utilization value and broad potential application. [ABSTRACT FROM AUTHOR]

The charge density, differential charge density, band structure, density of states and absorption spectra of cubic structure Ag3PO4 were calculated by Material Studio software. The best function for calculating the Ag3PO4 crystal model is PBE0 with a lattice constant of 6.004 Å. In Ag3PO4 crystal system, the force between O–Ag is weaker than that between O–P, which leads to the photo-corrosion of Ag3PO4 material. The forbidden band width of the Ag3PO4 crystal is 2.47 eV. The light absorption boundary is approximately 520 nm. At the same time, the cubic phase Ag3PO4 was successfully prepared. The light absorption boundary value of the Ag3PO4 sample measured by UV–Vis diffuse reflectance spectroscopy is about 520 nm, and the forbidden band width is 2.41 eV. The results obtained by means of photoluminescence spectroscopy, UV–Vis diffuse reflectance absorption spectroscopy and degradation of organic pollutants are consistent with theoretical calculations. calculations. [ABSTRACT FROM AUTHOR]

Se sintetizaron nanovarillas de óxido de manganeso en fase cristalina beta (β-MnO2). Microscopía electrónica de barrido (SEM) y difracción de rayos-X (XRD) confirmaron la morfología y fase cristalina, respectivamente. Mediante la teoría del funcional de densidad (DFT), se calcularon las propiedades mecánicas teóricas de β-MnO2 con el programa CASTEP. Se realizó una optimización de la geometría de la celda unitaria, determinándose las constantes elásticas Cij, calculándose los valores del módulo de Young y de corte, y el coeficiente de Poisson, entre otros. Los resultados fueron comparados con los valores reportados en la literatura, encontrándose una significante similitud en los parámetros analizados. Las relaciones de Cij indicaron la aceptación de los criterios de Born, confirmando la estabilidad de la estructura cristalina de β-MnO2. La constante C44, así como el módulo de volumen y de corte, mostraron valores grandes, lo que indica un material con considerable dureza. Este comportamiento fue confirmado con el valor obtenido de la razón del módulo de volumen entre el módulo de corte por la aproximación de Hill. El entendimiento de las propiedades calculadas en este estudio usando CASTEP permitirá obtener parámetros adicionales de propiedades ópticas, termodinámicas, entre otras, así como el desarrollo de modelaciones y simulaciones que permitan entender y aplicar los conocimientos adquiridos a aplicaciones reales (experimentales), p. ej., en la remoción de contaminantes.

In this work, the structure, phase composition, hardness and tensile strength of the AlMgB14-based material obtained by spark plasma sintering (SPS) were investigated. According to the XRD results, the spark plasma sintered material contains 94 wt% AlMgB14 phase and 6 wt% spinel MgAl2O4. Analysis of the SEM images showed that the obtained AlMgB14 sample has a dense structure; the relative density of the sample is 98.6%. The average microhardness of the spark plasma sintered (SPSed) sample is 29 ± 0.88 GPa. According to the results of the Brazilian test, the tensile strength of AlMgB14 is 56 MPa. The fracture is characterized by a single straight tensile crack that divides the sample along the compression line into two halves. The type of fracture in the AlMgB14 sample can be characterized as a cleavage fracture due to crack growth occurring in accordance with the transcrystalline fracture. The tensile strength of the obtained material is in good agreement with the tensile strength of boride and oxide ceramics studied in other works.