Pugh Ratio Research Articles

Strain effect on the physical properties of novel Mg3NI3 perovskite material: First principle DFT analysis

Inorganic perovskite-based substances have become a major attraction to solar technology. Inorganic cubic perovskites have generated a heap of fascination owing to their distinctive optical, electrical, and structural features. The photovoltaic and optoelectronic industries prioritize lead-free, atomically tailored metal halide perovskites due to the need to address lead (Pb) toxicity and instability. This study assessed the optical, structural, and electrical parameters of Pb-free inorganic halide perovskites as a function of biaxial compressive and tensile strain, leveraging first-principles density-functional theory (FP-DFT). Refractive index, absorption coefficient, reflectivity, dielectric function, and tolerance factor are a few additional optical parameters that are computed and processed. The bandgap of the planar molecule is 0.412 eV (PBE) when SOC is not applied. The bandgap reduces to 0.363 eV (PBE) at its Γ(gamma) and R-point when the subjective SOC effect is taken into consideration. This compound's bandgap will narrow under tensile strain and expand under compressive strain, depending on whether the SOC effect is applied or not. Several elastic factors are anticipated, including the bulk modulus, Pugh's ratio, elastic constants, anisotropic factors, and Poisson's ratio. Electronic property calculations using band mechanism and density of states (DOS) suggest that have a bandgap that is indirect and semiconductive. The elastic properties of this material were found to be mechanically stable, anisotropic, and ductile. In the photon energy range suitable for solar cells, the spikes in the dielectric constant of are seen. Our findings point to the prospect of as a non-toxic, high-performance, low-cost material for implementation in solar cells and different semiconductor devices.

DFT simulations of the elastic, optoelectronic, and thermoelectric attributes of AOsCl3 (A = K, Rb), a robust and environmentally friendly perovskites for green energy implications.

Halide perovskites are an intriguing renewable energy materials that may assist in addressing the world's energy scarcity. The Goldsmith tolerance factor (0.99 and 1.00) and negative formation energy guarantee the examined materials' structural and thermodynamic stabilities. The Poisson's and Pugh's ratio proves the reviewed materials' ductile nature. K/RbOsCl3 has electronic band gaps of 1.37eV/1.39eV and the highest light absorption in the ultraviolet and visible areas, enhancing its efficacy for solar cells and other optoelectronics technologies. The highest Seebeck coefficient and electrical conductivity render these materials feasible for thermoelectric properties. KOsCl3 and RbOsCl3 exemplify figures of merit of 0.89 and 0.88, respectively, at the ambient temperature. Additionally, the Debye model was implemented to figure out thermodynamic parameters such as heat capacity, thermal expansion, Debye temperature, and Grüneisen parameter.

Understanding the pressure effect on the physical properties of half-Heusler semiconductor LiCaX (X = As, Sb, N) compounds from Ab-initio calculations

The study delves into the structural, elastic, electronic, thermodynamic, and lattice dynamical and optic properties of LiCaX (X = As, Sb, N) ternary half-Heusler compounds under varying pressure and temperature conditions. Employing density functional theory with the generalized gradient approximation (GGA) in VASP codes, the initial steps involve optimizing the structure of the compound (cubic MgAgAs-type, space group F43m, C1b), determining elastic constants (C11, C12, and C44), and calculating elastic moduli (bulk modulus, shear modulus, Young's modulus). Other mechanical parameters such as Pugh's ratio, Poisson's ratio, and Zener anisotropy factor are also derived, providing insights into the brittle/ductile characteristics and isotropic/anisotropic behavior. The study further explores different vibrational modes in the compounds, and the effects of pressure on elastic anisotropy, vibrational, and optical properties are thoroughly investigated. Utilizing the quasi-harmonic Debye model, the research successfully reports V/Vo, bulk modulus, thermal expansion coefficient, and heat capacity at constant volume over a temperature range from 0 to 1000 K. The variation of photon energy is analyzed concerning the real and imaginary parts of the dielectric constant, refractive indices, extinction coefficient, reflectivity, and energy loss function up to 20 eV. The findings encapsulate the fundamental physical properties of all considered compounds, concluding with suggestions for potential future research avenues.

MAX phase borides, the potential alternative of well-known MAX phase carbides: A case study of V2AB [A = Ge, P, Tl, Zn] via DFT method

This study predicted four new MAX phase borides via the DFT method, with a comprehensive and thorough approach. The stability of the predicted phases has been thoroughly studied using formation energy, phonon dispersion curve (PDC), and elastic constants (Cij). The metallic nature of the studied phases is confirmed through the computation of the electronic band structure and density of states (DOS). Their bonding nature is disclosed using the partial density of states, Mulliken population analysis, and charge density mapping. The mechanical behavior is investigated in depth by calculating elastic constants, elastic moduli, Poisson's & Pugh ratio, machinability index, and Vickers hardness. Different anisotropic indices are also computed to demonstrate the elastic anisotropy. The Debye temperature (ΘD), Grüneisen parameter (γ), phonon thermal conductivity (kph), minimum thermal conductivity (kmin), thermal expansion coefficient (TEC), and melting temperature (Tm) are all calculated, and the suitability of the studied phases as thermal barrier coating (TBC) materials has been discussed. Finally, the optical constants are calculated and analyzed, further certifying the metallic nature of the herein-studied phases. The reflectivity spectra of all the herein selected compounds reveal their potential as coating materials to lessen solar heating. Among the studied phases, V2PB exhibits the best thermo-mechanical properties for potential applications in diverse fields, such as structural components and TBC materials. The potential applications of our findings are vast, and the obtained results reveal that the predicted phases are indeed potential alternatives to their counterpart carbides.

DFT investigation of thermodynamic, electronic, optical, and mechanical properties of XLiH3 (X= Mg, Ca, Sr, and Ba) hydrides for hydrogen storage and energy harvesting

The present study investigates the hydrogen storage capacity and physical properties of the perovskite hydrides XLiH3 (X = Mg, Ca, Sr, and Ba). The studied compounds MgLiH3, CaLiH3, SrLiH3, and BaLiH3 have lattice constants 3.76, 4.29, 4.64, and 5.04 Å, respectively. These compounds are also observed to be stable in cubic phase under atmospheric pressure and temperature conditions. They have hydrogen storage capacities 8.76 wt%, 5.99 wt%, 3.07 wt%, and 2.03 %, respectively. The SrLiH3 compound has the greatest Debye temperature (θD) of 344.41 K. The analysis of the electronic band structure and density of states reveals that perovskite hydrides have semiconducting characteristics with indirect band gap values of 2.66, 2.34, 1.94, and 1.37 eV, respectively. The materials are semiconductors and have suitable band gaps to be utilized in optical devices. Therefore, the optoelectronic properties of dielectric constants, absorption, and energy loss have been determined to predict the potential of materials for optoelectronic applications. Furthermore, the elastic constants, moduli, and anisotropy are also calculated for the observed materials. The Possion and Pugh ratios indicate these compounds exhibit ductile behaviour and significant anisotropy. Therefore, large values of hydrogen capacities, stabilities, and extraordinary physical behaviour make them important for hydrogen storage systems.

Optimization of cubic SrZrO3 perovskite oxides under varying stress conditions for high-performance optoelectronic devices: a DFT study

PurposeThe study highlights our findings, including the confirmation of phase stability through XRD analysis, the characterization of optical properties revealing high absorption and conductivity and the analysis of mechanical stability through elastic constants. Additionally, we present detailed results on the band gap, EELS analysis and the suitability of SrZrO3 perovskite oxides for next-generation optoelectronic devices.Design/methodology/approachCubic SrZrO3 perovskite oxides were designed within the framework of density functional theory (DFT) via the CASTEP code under varying stress conditions (0–100 GPa), aiming to explore the key properties for diverse applications. The phase stability was confirmed by XRD analysis. From 0 to 40 GPa, there is an increase in the band gap from 3.330 to 3.615 eV, while it narrows from 3.493 to 3.155 eV beyond 60 GPa. The optical characteristics revealed high absorption, superior conductivity and a lower loss function. Significantly, the elastic constants (C11, C12 and C44) satisfy the Born-stability criterion, ensuring the mechanical stability of the compound. Additionally, the Poisson’s ratio, Pugh ratio (B/G), Frantsevich ratio, Cauchy pressure (PC) and anisotropy factor ensured both ductile and anisotropic characteristics. Higher values of Young’s modulus and shear modulus signify a superior ability to withstand longitudinal stresses. In the EELS analysis, distinctive energy-loss peaks resulting from absorption and emission correlated with diverse electronic transitions and energy levels associated with Sr, Zr and O atoms are used to probe the precise exploration of the electronic and optical characteristics of materials with a high degree of accuracy. Based on these findings, the designed SrZrO3 perovskite oxides are particularly suitable for applications in various optoelectronic devices.FindingsCASTEP codes were utilized to design the cubic SrZrO3 perovskite under varying stress conditions ranging from 0 to 100 GPa. The phase stability was confirmed through XRD analysis. A distinctive trend in the band gap was observed: an increase from 3.330 eV to 3.615 eV as the stress increased from 0 to 40 GPa and a decrease from 3.493 to 3.155 above 60 GPa. A higher absorption and conductivity and a lower loss function were found for the optical properties. The mechanical stability was ensured by elastic constants (C11, C12, and C44) satisfying the Born-stability criteria. Additionally, the Poisson’s ratio, Pugh’s ratio (B/G), Frantsevich ratio, Cauchy pressure (PC) and anisotropy factor were used to verify the ductility and anisotropy of the materials. Higher values of Young’s modulus and shear modulus indicate a superior ability to withstand longitudinal stresses. EELS analysis revealed distinctive energy-loss peaks associated with Sr, Zr and O atoms, enabling precise exploration of the electronic and optical characteristics with a high degree of accuracy. As expected, the designed SrZrO3 perovskite oxides exhibit favorable properties, making them particularly suitable for next-generation optoelectronic devices.Originality/valueIn this study, we utilized DFT within the CASTEP code framework to investigate the properties of cubic SrZrO3 perovskite oxides under varying stress conditions ranging from 0 to 100 GPa. Our research aimed to explore the key properties of SrZrO3 for diverse applications, particularly in optoelectronic devices.

DFT study of halogen based double perovskite Na2AgAlX6 (X = Cl, Br, I) double perovskites for energy harvesting applications

Abstract Double perovskites halides show a lot of potential for being utilized in energy converting applications. This research offers a wide-ranging analysis of photovoltaic features of halogen based double perovskite Na2AgAlX6 (X = Cl, Br, I) by employing DFT approach. Structural, thermoelectric and optoelectronic features of Na2AgAlX6 have been analyzed in this report. The structural stability of the investigated materials is verified by Born's stability criterion. The ductility of Na2AgAlX6 is confirmed by the Poisson coefficient ( >0.27) and a Pugh ratio (B/G>1.83). The bandgap 3.7 eV, 2.7 eV, and 1.3 eV of Na2AgAlX6 (X = Cl, Br, I) has been observed with direct nature. The replacement of Br and I with Cl leads to the lowering of bandgap value because it brings the edges of the band closer together. The absorption factor, reflective properties, and dielectric parameters are used to evaluate the optical features. The BoltzTraP software played vital role in calculating the thermoelectric characteristics, such as ZT value, power factor, and their electrical and thermal conductivities.The results of these calculated properties indicate that Na2AgAlX6 (X = Cl, Br, I) double perovskite halides show a promising potential for energy renewable applications.

Theoretical investigations of optoelectronic properties, photocatalytic performance as a water splitting photocatalyst and band gap engineering with transition metals (TM = Fe and Co) of K3VO4, Na3VO4 and Zn3V2O8: a first-principles study.

First-principles density functional investigations of the structural, electronic, optical and thermodynamic properties of K3VO4, Na3VO4 and Zn3V2O8 were performed using generalized gradient approximation (GGA) via ultrasoft pseudopotential and density functional theory (DFT). Their electronic structure was analyzed with a focus on the nature of electronic states near band edges. The electronic band structure revealed that between 6% Fe and 6% Co, 6% Co significantly tuned the band gap with the emergence of new states at the gamma point. Notable variations were highlighted in the electronic properties of Na3V(1-x)Fe x O4, Na3V(1-x)Co x O4, K3V(1-x)Fe x O4, K3V(1-x)Co x O4, Zn3(1-x)V2(1-x)Co x O8 and Zn3(1-x)V2(1-x)Fe x O8 (where x = 0.06) due to the different natures of the unoccupied 3d states of Fe and Co. Density of states analysis as well as α (spin up) and β (spin down) magnetic moments showed that cobalt can reduce the band gap by positioning the valence band higher than O 2p orbitals and the conduction band lower than V 3d orbitals. Mulliken charge distribution revealed the presence of the 6s2 lone pair on Zn, greater population and short bond length in V-O bonds. Hence, the hardness and covalent character develops owing to the V-O bond. Elastic properties, including bulk modulus, shear modulus, Pugh ratio and Poisson ratio, were computed and showed Zn3V2O8 to be mechanically more stable than Na3VO4 and K3VO4. Optimal values of optical properties, such as absorption, reflectivity, dielectric function, refractive index and loss functions, demonstrated Zn3V2O8 as an efficient photocatalytic compound. The optimum trend within finite temperature ranges utilizing quasi-harmonic technique is illustrated by calculating thermodynamic parameters. Theoretical investigations presented here will open up a new line of exploration of the photocatalytic characteristics of orthovanadates.

Ultrahigh carrier mobility and anisotropy of the layered semiconductor ATiN2 (A = Ca, Sr and Ba)

Semiconductors with a suitable band gap and high carrier mobility are highly desirable in the electronics, optoelectronic and photovoltaic applications. The mechanical, electronic, optical and transport properties of the layered nitrides ATiN2 (A = Ca, Sr, and Ba) have been systematically studied by theoretical calculations. These nitrides show good ductility with moderate moduli, larger Poisson's ratio than 0.26 and Pugh's modulus ratio exceeding 1.75. CaTiN2 and SrTiN2 are direct bandgap semiconductors, while BaTiN2 is an indirect bandgap semiconductor, showing suitable band gaps (1.54–1.78 eV) and band edge positions for optoelectronic and photocatalytic water-splitting applications. More intriguingly, they possess superhigh carrier mobility with remarkable anisotropy. Particularly, the in-plane electron mobility reaches an ultrahigh order of 104 cm2V−1s−1, whereas those along the out-of-plane direction are almost zero. In addition, the hole mobilities are also very large along the in-plane direction and the anisotropic ratios are as high as about 30 for all these nitrides. Furthermore, these ATiN2 nitrides exhibit high optical absorption coefficients (∼105 cm−1) and lower exciton binding energies. Due to the suitable band gaps and band alignments, ultrahigh carrier mobility and huge anisotropy, excellent visible light absorption performance, the ATiN2 nitrides will be promising candidate semiconductors in electronics, optoelectronic, photovoltaic and photocatalytic applications.

First-Principles Calculations of the Structural, Mechanical, Optical, and Electronic Properties of X2Bi4Ti5O18 (X = Pb, Ba, Ca, and Sr) Bismuth-Layered Materials for Photovoltaic Applications

For the first time, density functional theory (DFT) calculations have been employed for the measurement of the structural, mechanical, optical, and electrical properties of a bismuth-layered structure ferroelectrics (BLSFs) family member possessing an orthorhombic structure with Cmc21 space group. Based on the exchange–correlation approximation, our calculations show that Pb2Bi4Ti5O18 possesses an indirect band gap, while the materials X2Bi4Ti5O18 (X = Ba, Ca, and Sr) demonstrate direct band gap, where the estimated density functional fundamental band gap values lie between 1.84 to 2.33 eV, which are ideal for photovoltaic applications. The optical performance of these materials has been investigated by tuning the band gaps. The materials demonstrated outstanding optical characteristics, such as high absorption coefficients and low reflection. They exhibited impressive absorption coefficient (α = 105 cm−1) throughout a broad energy range, especially in the visible spectrum (105 cm−1 region). The findings show that the compounds demonstrate lower reflectivity in the visible and UV regions, making them suitable for single-junction photovoltaic cells and optoelectronic applications. The Voigt–Reuss–Hill averaging technique has been employed to derive elastic parameters like bulk modulus (B), Young’s modulus, shear modulus (G), the Pugh ratio (B/G) and the Frantesvich ratio (G/B) at 0.1 GPa. The mechanical stability of the compounds was analyzed using the Born stability criteria. Pugh’s ratio and Frantesvich’s ratio show that all the compounds are ductile, making them ideal for flexible optical applications.

Exploring the inorganic perovskite materials Mg3SbX3 (Where, X=I, Br, Cl and F) through the perspective of density function theory: Adjustment of physical characteristics as consequence of strain

The solar technology industry has lately given inorganic perovskite materials an abundance of thought because of their unique optical, electrical and structural characteristics. Issues pertaining to lead (Pb) toxicity and instability require being referred to promptly, making lead-free atomically designed metal halide perovskites of foremost importance to the photovoltaic and optoelectronic industries. Perovskites, a class of inorganic metal halide semiconductors, have variant similarities with (X=I, Br, Cl and F). According to the space group Pm-3m (X=I, Br, Cl and F) has a cubic perovskite crystal structure. Utilizing first-principles density-functional theory (FPDFT), The intention of this investigation is to analyze how strain and spin-orbit coupling (SOC) impact the structural, electrical, optical and mechanical features of the inorganic cubic perovskite of (X=I, Br, Cl and F). At the point between R and Γ, the molecule displays an indirect bandgap of 0.105 eV, 0.957 eV, 1.728 eV. At the Γ point, the molecule displays a direct bandgap of 3.184 eV. The bandgaps of the and perovskites are 0.198 eV, 1.203 eV, 1.901 eV and 3.723 eV respectively, when considering the spin-orbital coupling (SOC) quantum influence. A wider bandgap is investigated for increasing compressive strain while a smaller bandgap is observed for increasing tensile strain. Apart from the elastic constants and anisotropic factors, other factors that are anticipated include Pugh's ratio, Poisson's ratio, bulk modulus and others. Isotropic, ductile and mechanically stable are the words that best describe these materials, according to the elastic property evaluations. In the photon energy range that is appropriate for solar cells, the dielectric constant spikes of are found to be visible. Therefore, (X=I, Br, Cl and F) perovskite is a good material to use in solar cells for managing light and producing electricity.

First-principles calculations to investigate physical properties of oxide perovskites LaBO3 (B[dbnd]Mn, Fe) for thermo-spintronic devices

Oxide perovskite LaBO3 was extensively examined using first principles computations with density functional theory. Various exchange-correlation functionals were applied to investigate several of its physical properties. The compound's stability was validated through energy optimization in both ferromagnetic and non-magnetic phases, revealing that the ferromagnetic phase is more energetically stable. With the optimized lattice parameter, we explored various electronic, mechanical, magnetic, and thermodynamic properties. According to the GGA + U approximation, LaMnO3 and LaFeO3 exhibit half-metallic and semiconductor characteristics, respectively. The elastic constants, along with the elastic moduli (Y, B, and G) and Vickers hardness (Hv) number, were calculated to assess the mechanical properties of both compounds. Our simulation confirmed the ductile nature of the material by analyzing the Cauchy pressure, Poisson's ratio, and Pugh ratio. Additionally, thermodynamic parameters, including thermal expansion, specific heat capacity, and Debye temperature, were computed using the quasi-harmonic Debye model. The study's findings suggest that these materials are suitable for thermo-spintronic devices.

Semiconductor-metal transition in TlPbF3 under isotropic pressure and its impact on optical, elastic and mechanical properties: a DFT computation with HSE06

This research aims to comprehensively evaluate the structure, elasticity, mechanics, anisotropy, electrical properties, and optical attributes of TlPbF3 at pressures from 0 to 60 GPa. A cubic structure of the material remains same without any phase changes, but there is a reduction in the lattice parameters. The material is determined to be mechanically secure by doing calculations on a variety of mechanical and elastic characteristics, including bulk, shear, and Young’s modulus, stiff, and not particularly flexible. It also shows a significant resistance to shear force. The material’s ability to withstand high pressures, its metallic bond nature, and ductility have been shown by the Kleinman’s parameter, Poisson’s ratio, Cauchy pressure, and Pugh ratio. Anisotropy can be confirmed by activating specific anisotropy factors. When we consider the electronic band structure, we observe a transition from a broad gap in the band (3.719 eV) comparable with a small band distance (0.65 eV), and converts to a metal (0 eV). To explore this, we have estimated the total, partial and elemental partial density of states. Additionally, we have computed the real and imaginary functions of dielectric, absorption factor, refractive index, extinction coefficient, loss function, reflectivity and real/imaginary conductivity to assess the material’s applicability. As pressure is applied, the static values of ε1(ω) and n(ω) increase. This material is also well-suited for optoelectronic devices due to its high conductivity, reflectivity, absorption, and refractive index.

Investigation of structural, elastic, electronic, and optical properties of lead-free double perovskites Cs2XBeBr6 (X = Ge, Sn): a first-principles DFT study.

In this study, the structural, elastic, electronic, and optical properties of Cs2GeBeBr6 and Cs2SnBeBr6 halide double perovskites (HDPs) were investigated using density functional theory (DFT) calculations. Notably, the Tran-Blaha modified Becke-Johnson (TB-mBJ) method was employed to predict indirect band gaps of 2.434 eV for Cs2GeBeBr6 and 2.855 eV for Cs2SnBeBr6. The stability of these compounds in a cubic (Fm-3m) structure was confirmed through formation energy, cohesive energy, tolerance factor, and elastic constants. Furthermore, the ductile nature of the materials was demonstrated through Poisson's and Pugh's ratios. Our optical property analysis, spanning the 0-13 eV energy range, revealed key insights into the dielectric functions, extinction coefficient, electron energy loss, refractive index, optical conductivity, reflectivity, and absorption coefficient. These results highlight the potential of Cs2GeBeBr6 and Cs2SnBeBr6 for future optoelectronic and photovoltaic applications. In this investigation, we employed density functional theory (DFT), implemented using the Wien2k package. The exchange and correlation potentials were treated using the generalized gradient approximation (GGA) and the Tran-Blaha modified Becke-Johnson (TB-mBJ) method. To evaluate dynamic stability, we analyzed the phonon band structures using the CASTEP code.

Computational study of Rubidium-Rb based cubic Rb2TlCoF6 double perovskite material for photocatalytic water degradation applications: A DFT investigations

The fascinating characteristics, such as straightforward and stable crystal structure, and double perovskites are currently popular materials for applications in renewable energy. In our study, we applied CASTEP and DFT, called density functional theory, to theoretically investigate the mechanical, optical, and thermoelectric characteristics of cubic Rb2TlCoF6. Calculations of the compound Rb2TlCoF6's structural, electrical, optical, mechanical, and thermodynamic properties are made using the GGA-PBE exchange correlational functional and the Fm3m with space group no.225 vol and compound lattice constant are 9.08 Å and 748.613 Å3, respectively. For Rb2TlCoF6, the measured energy band gaps are 1.45 eV. The mechanical and elastic constants are calculated to confirm the ductile properties of Rb2TlCoF6. The brittle characteristics have been verified using Passion and Pugh's ratios, which are 1.67 and 0.25, according to elastic constants. Vickers compound hardness Hv and anisotropy factor “A” are 4.19 and 0.77, respectively. The compounds' optical characteristics reveal significant conductivity and absorption. The compound exhibits high-efficiency photocatalytic activity based on its optical characteristics. Based on mechanical stability, such as Debye temperature, melting temperature, minimum thermal conductivity, average sound velocity, free energy, and other variables, the thermodynamic and structural stabilities are calculated. These materials controlled electrical and other properties make them potentially useful in photocatalytic applications. According to the outcomes, Rb2TlCoF6 is appropriate for photocatalytic water-splitting applications and water deterioration.

Hydrostatic Pressure‐Tuning of Opto‐Electronic and Thermoelectric Properties Half‐Heusler Alloy RhTiP With DFT Analysis

ABSTRACTUtilizing DFT along with Boltzmann transport theory, the structural, elastic, electrical, optical, and thermoelectric properties of half‐Heusler compound RhTiP have been calculated in principle to examine the pressure effect in the range of 0–40 GPa. As pressure increases, the volume and normalized lattice parameter decreased. In addition to satisfying the Born stability criterion, which ensured the compound RhTiP “natural stability,” the zero pressure elastic constants and the pressure‐dependent elastic constants are positive up to 40 GPa. The band structure computations guarantee the semiconductor nature of RhTiP, as demonstrated by the presence of electronic band gap of 1.035 eV at zero pressure. Using the Voigt‐Reuss‐Hill (VRH) averaging scheme under pressure, we have determined the values of this compound's bulk modulus , shear modulus , Young's modulus , Pugh ratio , Poisson's ratio , and anisotropy factor . Because the bulk modulus responds linearly to pressure, the material's hardness increases as pressure rises. Additionally, under pressures up to 40 GPa, the optical characteristics of RhTiP, including their reflectivity, absorptivity, conductivity, dielectric constant, refractive index, and loss function, were assessed and discussed. Furthermore, the thermoelectric properties are also studied for the materials and supports the tunning of pressure. This study provides a gateway to how the optoelectronic and transport properties of cubic RhTiP could be tuned by employing external pressure.

First-principle study on the structural, electronic and mechanical properties of High Entropy Alloy TiZrFeRu for hydrogen storage applications

High-entropy alloys are promising for hydrogen storage, especially in terms of their tunable hydrogen storage properties. Although several experimental studies, a fundamental and detailed atomistic comprehension of physical and electronic of the hydrogenation process is still lacking. This work investigated the structural, electronic and mechanical properties of TiZrFeRu high-entropy alloys (HEAs) using first-principle calculation. Indeed, we employed both density functional theory and density functional perturbation theory in the calculations with generalized gradient approximation and plane-waves pseudo-potential formalism. In addition, we used Virtual crystal approximation (VCA) to describe HEA as is well suited for predicting elastic properties. We have calculated relevant physical parameters, including lattice constants, elastic constants, elastic modulus, Poisson's ratio, Pugh's ratio, anisotropy factors and Vickers hardness..etc. Our calculated finding show that that TiZrFeRuH2 is mechanically stable and has a good ductility with a Pugh’s ratio (B/G) greater than 1.75. Lastly, we investigated and discussed electronic bandstructure, the total and partial electronic density of state. The results indicate that this compound exhibit a metallic character concentrated in a zone between -5 and 5 eV. The value of the Poisson ration (0.35) confirm again that this compound is metallic (for metal materials the Poisson ratio is above 0.25).

Exploring Rb2YCuCl6 and Cs2YCuCl6 double perovskites: Structural, electronic, optical, elastic, and thermoelectric properties via density functional theory

Double perovskites have gathered momentous attention due to their structural, optoelectronics, and thermal properties. FP-LAPW + lo technique was employed along with the PBEsol-GGA and TB-mBJ potential. The optimized parameters and E-V parabolic curve were computed employing Birch Murnaghan's equation of state (BM-EOS). The negative formation energy Ef for Rb2YCuCl6 and Cs2YCuCl6 confirms the thermodynamic stability of these double perovskites. The mechanical stability of both compounds was confirmed by their elastic constants Cij, Pugh's ratio, and anisotropy. The indirect band plots of Rb2YCuCl6 (2.57eV) and Cs2YCuCl6 (2.39eV) double perovskites confirm the semiconductor nature. The optical properties like dielectric function, reflectivity, optical conductivity, absorption coefficient, and energy loss function were determined within an energy range of up to 18 eV. The high absorption spectra for the under-study compounds 147.21 × 104 cm−1 at 14.60 eV for Rb2YCuCl6 and 261.30 × 104 cm−1 at 15.57 eV for Cs2YCuCl6 lies in the far UV region determines its potential use in the high-frequency devices. The thermoelectric properties such as the Seebeck coefficient, ZT, and power factor, are investigated using the semi-classical Boltzmann theory implemented in the BoltzTrap code. The peak value of ZT for Rb2YCuCl6 is 0.38 and for Cs2YCuCl6 is 0.33. The suggested findings indicate that Rb2YCuCl6 and Cs2YCuCl6 are potential candidates for thermoelectric and photovoltaic applications.

Exploring changes in structural, electronic and elastic properties of TiO2 under pressure: A DFT investigation

Titanium dioxide (TiO2) is a semiconductor material that widely used in numerous applications due to its exceptional physical and chemical properties. This study explores the structural, electronic and elastic properties of TiO2 phases in rutile, anatase and brookite under hydrostatic pressure up to 100 GPa. At 0 GPa, the computed lattice parameters and volumes align closely with experimental data. The band structure reveals that rutile and brookite exhibit direct band gaps while anatase shows an indirect band gap. Elastic properties including bulk modulus, shear modulus, Young’s modulus, Cauchy pressure, Pugh ratio and Poisson’s ratio were calculated using the Voigt-Reuss-Hill approximation. Our findings confirm the mechanical stability of all TiO2 phases and offer insights that align with existing theoretical and experimental data. These findings provide a comprehensive understanding of behavior of TiO2 under high-pressure condition which is crucial for optimizing its applications in various fields such as photocatalysis and solar cells.

A DFT investigation of Li substitution in CsCaY3 (Y[dbnd]F, Cl, Br) having admirable optoelectronic characteristics as a viable candidate for photocatalytic water splitting

In this study we investigated pristine and Li substituted Cs1-xLixCaY3 (YF, Cl, Br) lead free halide perovskite with different concentrations x = 0, 0.11, 0.33, 0.55, 0.77, and 1 using CASTEP under Density functional theory (DFT) has been employed under Perdew Burke Ernzerhof generalized gradient approximation (GGA-PBE) and Ultrasoft pseudo potential (USSP) approaches. Understudy pristine materials have a cubic phase Pm3 m space group. At the same time, doped compositions show a tetragonal phase structure except those in which Li completely swaps out Cs, so both end materials own a cubic nature. Li introduced at the Cs site is more effective than Ca because additional gamma points formed, influencing the electronic formation of pristine CsCaF3, CsCaCl3, and CsCaBr3 minimized band gap from 6.299 to 4.152 eV, 5.261–3.613 eV and 4.338–2.752 eV respectively. All compositions are thermodynamically stable, as suggested by the negative values of the formation energy. For all compositions, the Fermi level resides near the valence band which confirms the p-type behavior of the semiconductors. All of the materials retain the indirect bandgap. The total/partial/elemental density of states calculated has been approximated to provide a full picture of the band structure. Although elastic constants for all compounds, whether cubic or tetragonal, are used to predict mechanical parameters such as bulk modulus, shear modulus, young modulus, Poisson ratio, and Pugh's ratio, materials were first developed to support born stability criteria. From all of the compositions Cs1-xLixCaF3 for x = (0.11, 0.55, 0.77, and 1) and Cs0.23Li0.77CaCl3 are found to be mechanically unstable. All other combinations are stable, whether cubic or tetragonal. We evaluated and contrasted many optical properties like absorption spectra, refractive index, dielectric function, reflectivity, and energy loss function of pristine CsCaY3 (YF, Cl, Br) in comparison with Li substitution concentrations. For both pristine and Li substituted CsCaY3 (YF, Cl, Br) the overall water splitting was explored. All the compositions can be used for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting reactions but Cs0.23Li0.77CaBr3 is a good catalyst among all. It is proposed that the aforementioned materials have a bandgap range suitable for solar cell applications in addition to being lead-free for environmentally conscious applications in photocatalytic activity.