Born Stability Criteria Research Articles

Elucidating the Structural, Electronic, Elastic, and Optical Properties of Bulk and Monolayer MoS2 Transition-Metal Dichalcogenides: A DFT Approach.

Due to their outstanding properties for optoelectronic and versatile electronic applications, the atomically thin layers of transition-metal dichalcogenide (TMDC) materials have demonstrated a potential candidacy to succeed its analog silicon-based technology. Hence, the elucidation of the most important features of these materials is indispensable. In this study, we provide a theoretical elucidation of the structural, electronic, elastic, and optical characteristics of TMDCs. The study has been carried out by elucidating the material in its two particular forms, namely, bulk and two-dimensional (2D) layered (monolayer). The theoretical investigation was carried out within the framework of the density functional theory (DFT) method using first-principles calculations. The Perdew-Burke-Ernzerhof (PBE) variant of the generalized gradient approximation (GGA) scheme, as performed in the Quantum Espresso package, is used. Van der Waals density functional effects, involving the nonlocal correlation part from the rVV10 and vdW-DF2 methods, were treated to remedy the lack of the long-range vdW interaction. An illustration of the performance of both rVV10 and vdW-DF2 functionalities, with the popular PBE correlations, is elucidated. The Born stability criterion is employed to assess structural stability. The obtained results reveal an excellent stability of both systems. Furthermore, the theoretical results show that band-gap energy is in excellent agreement with experimental and theoretical data. Pugh's rule suggested that both the bulk and MoS2-2D layered systems are ductile materials. The refractive indices obtained herein are in good agreement with the available theoretical data. Moreover, the theoretical results obtained with the present approach demonstrate the ductility of both systems, namely, the bulk and the MoS2-2D layered. The results obtained herein hold promise for structural, elastic, and optical properties and pave the way for potential applications in electronic and optoelectronic devices.

Understanding the impact of Y2+ (Y[dbnd]Mn, Fe, and Co) cations on physical properties of SrYGe2O6 clinopyroxene: A DFT insight

Pyroxenes are one of the most important minerals in igneous rock with extremely varied compositions. Here, the structural, mechanical, magnetic, thermodynamic, and optoelectronic features of the SrYGe2O6 (Y= Mn, Fe, and Co) in the monoclinic phase is presented by the density functional theory (DFT) investigation. The generated structures using GGA-PBE, GGA-PBSOL, and LDA exchange-correlation functional in a ferromagnetic ordering have lattice parameters that agree with the existing experimental data. All of the three structures are found mechanically stable by Born stability criteria. The most ductile material is SrCoGe2O6, whereas Poisson's ratio (σ) predicts that SrMnGe2O6 is brittle. These have metallic nature for one spin state and semiconducting for another spin state, which confirms the half-metallic or half semiconducting nature. The direct type half-metallic gap for SrCoGe2O6, SrMnGe2O6 and SrFeGe2O6 are found as 1.76 eV, 1.252 eV, and 0.701 eV, respectively. A deep electronic structural configuration is analyzed by the bond population analysis. Effective masses of charge carriers and exciton binding energies revealed insight into the transport properties. The structures exhibit significant UV photon absorption, high visible photon reflectivity, and plasmon peaks of about 13 eV were seen in estimated loss function spectra. These characteristics collectively point to possible applications for these pyroxenes in optoelectronics and spintronics.

Computational insights into the superior efficiency of Cs2AgGa(Cl,Br)6 double halide perovskite solar cells

Owing to their ecological integrity, non-toxicity, and outstanding performances, Double-Halide perovskites have been vigorously promoted as sustainable alternatives for thermoelectric and photovoltaic applications. In this context, we have systematically explored the structural and mechanical strength characteristics of Cs2AgGa(Cl,Br)6 materials through the tolerance factor analyses and Born stability criteria. Subsequently, a detailed study of their electronic, optical, and thermoelectric properties has been performed. As results, both Cs2AgGaCl6 and Cs2AgGaBr6 show semiconducting nature with a direct bandgap of about 2.57 eV and 1.42 eV, respectively. Additionally, with such desirable band gaps, the optical properties were examined based on the complex dielectric function. It has been derived that both materials exhibit a very high absorption spectrum in the order of 105 cm−1 and a low reflectivity not exceeding more than 18% in the visible and UV region. Furthermore, the Cs2AgGaBr6 has been taken into account as absorber to construct the planar p-intrinsic-n structure (FTO/TiO2/Cs2AgGaBr6/Spiro-OMeTAD/Au) and a high-record efficiency of 32.57% has been reached. The thermoelectric performance was also studied and revealed a very high Seebeck coefficient (thermo-power) and a sufficient figure of merit (ZT). Based on these results, we believe that the studied double-halide perovskites present outstanding performance for both optoelectronic and thermoelectric engineering devices.

The first-principle study on structural, mechanical, electronic and optical properties of half-metallic CaMSi2O6 (M= Co, Fe, Mn) clinopyroxenes

Ca-based pyroxene structures have gained significant attention due to the higher abundances of calcium in the earth's crust and relatively easy synthesis process. Here, we have analyzed the structural, mechanical, elastic, thermal, and optoelectronic properties of CaMSi2O6 (M = Co, Fe, Mn) pyroxene structures in the monoclinic phase using the first-principles density functional theory (DFT) approach using CASTEP code. The lattice constants of the simulated structures in ferromagnetic (FM) orientations using GGA-WC and GGA-PBSOL were consistent with the available experimental data. Using the Born stability criteria, these structures are considered mechanically stable. These are elastically anisotropic and brittle compounds. The melting temperatures are in the order of 103 K which symbolizes these as potential candidates for high-temperature applications. The band structure alongside the electronic density of states at the Fermi level reveals half metallicity of these structures. CaMnSi2O6 structure has a maximum half-metallic gap of around 4.60 eV. The remaining two structures have an indirect band gap in the visible photon range given as 3.14 eV, and 2.65 eV for CaCoSi2O6, and CaMnSi2O6, respectively. Observing optical and electronic properties shows that the compound holds a promising future to be utilized in the optoelectronic and plasmonic fields.

First-principles calculations to investigate structural, electronics, optical and mechanical properties of LaRu2P2 compound for superconducting application

ABSTRACT First-principles computations of the structural, electronic, optical and mechanical properties of LaRu2P2 compound are reported. The optimised lattice parameters match well with a previous study, which shows the authenticity of our calculations. The electronic properties indicate the metallic nature of material. At the Fermi level, the overlapping of conduction and valence band represents the metallic nature of the compound. The Mulliken population analysis is used to investigate the bonding nature in the compound. The optical properties indicate that in the low-energy region, LaRu2P2 has a strong absorption coefficient and a high refractive index. The mechanical stability is determined with the help of Born stability criteria and the compound is found mechanically stable. The ductile behaviour of the material was confirmed by Pugh’s and Poisson’s ratios. The mechanical properties show that the material is anisotropic in nature. Due to the superconducting nature of the compound, it may be utilised for superconducting applications.

High-pressure study of the aurophilic topological Dirac material AuI

We endeavour to explore the high-pressure study in the aurophilic AuI within the state-of-the-art of first principles. The impediment of expressing precise ground-state features of aurophilic compounds that had afflicted prior theoretical research has been resolved by incorporating van der Waals corrections (vdw). Mechanical and dynamical stability are ensured at ambient using the computed elastic constants and phonon dispersion curves. The dynamical instability is triggered by the application of pressure in AuI, as evidenced by the softening of an acoustic mode (Eu) at ∼7 GPa. Non-adherence of estimated elastic constants to the Born stability criterion at this pressure illustrates the system's mechanical instability. As previously demonstrated in experiments, the pressure-driven amorphization is rationalised by the phonon softening and elastic instability. Our calculations of the electronic band structure reveal an indirect bandgap (2.31 eV). Z2 invariants confirm that non-symmorphic AuI is a non-trivial Dirac material with the inclusion of spin-orbit coupling. Furthermore, a type-A hourglass dispersion with movable Dirac point is observed at the two-fold screw rotation axis (C2y). The pressure-dependent electronic structure reveal that the band topology is unaffected by pressure up to amorphous state. Our findings predict that this aurophilic class of material AuI possess exotic structural and electronic properties, encouraging further studies.

High Pressure Study of New Type of MAX Phases: Hf2AB2 (A = In, Sn)

This study carries out density functional theory (DFT)‐based simulation in order to observe the effect of pressure (up to 120 GPa) on the various physical properties of boron (B) containing new MAX compounds Hf2InB2 and Hf2SnB2. Structural parameters in ambient conditions show excellent concordance with prior experimental and theoretical data. A decreasing trend of lattice parameters with pressure is observed. The stability of the phases under pressure is determined by calculating the elastic constant using the Born stability criteria, and is found stable within the studied pressure range. Pressure's effect on the various elastic moduli is considered, and a linear response with pressure is observed. The brittle/ductile behavior under pressure is investigated, and a brittle to ductile phase transition is found. An opposite trend of elastic moduli with pressure is observed for Vickers hardness. The nonlinear variation of Vickers hardness with pressure has been interpreted in terms of Pugh ratio and density of states (DOS). A decreasing trend of the anisotropic indices is observed for Hf2InB2, while an increasing trend is observed for Hf2SnB2. The electronic and optical properties are also significantly influenced by the pressure. The results obtained at zero GPa have been compared with previous results and show significant agreement.

First-principles calculations to investigate structural, elastic, electronic, thermodynamic, and thermoelectric properties of CaPd3B4O12 (B = Ti, V) perovskites

This study has explored numerous physical properties of CaPd3Ti4O12 (CPTO) and CaPd3V4O12 (CPVO) quadruple perovskites employing the density functional theory (DFT) method. The calculated lattice constants show inclinable compliance with the experimental results that ensure their structural stability. The mechanical permanence of these two compounds was observed by the Born stability criteria as well. The mechanical and elastic behaviors have been rationalized to investigate elastic constants, bulk, shear, and Young’s modulus, Pugh’s ratio, Poisson’s ratio, and elastic anisotropy indexes. The ductility and anisotropic indexes confirm that both materials are ductile and anisotropic in essence. The band structure of CPTO reveals a 0.88 and 0.46 eV direct narrow band gap while using TB-mBJ and GGA-PBE potentials, respectively, which is an indication of its fascinating semiconducting nature. Whereas, CPVO perovskite exhibits a metallic character. The calculated partial density of states indicates the strong hybridization between Pd-4d and O-2p orbital electrons for CPTO, whereas Pd-4d and V-3d-O-2p for CPVO. The study of the chemical bonding nature and electronic charge distribution graph reveals the coexistence of covalent O-V/Pd bonds, ionic O-Ti/Ca bonds, as well as metallic Ti/V-Ti/V bonding for both compounds. The Fermi surface of CPVO ensures a kind of hole as well as electron faces simultaneously, indicating multifarious band characteristics. The prediction of the static real dielectric function (optical property) of CPTO at zero energy implies its promising dielectric nature. The photoconductivity and absorption coefficient of CPBO display good qualitative compliance with the consequences of band structure computations. The calculated thermodynamic properties manifest the thermodynamical stability for CPBO, whereas phonon dispersions of CPVO exhibit stable phonon dispersion in contrast to slightly unstable phonon dispersion of CPTO. The predicted Debye temperature (θD) has been utilized to correlate its topical features including thermoelectric behaviors. The studied thermoelectric transport properties of CPTO yielded a higher Seebeck coefficient (186 μV/K), power factor (11.9 μWcm−1K−2), and figure of merit (ZT) value of about 0.8 at 800 K, indicating that this material could be a promising candidate for thermoelectric applications.

Pressure effects on structural, electronic and anisotopic elastic properties of Si doped RuGe compound with different concentrations by first-principles calculations

In this study, we have performed first-principles density functional theory (DFT) calculations to investigate pressure and composition effects on the structural, elastic, and electronic properties of silicon doped RuGe ternary compounds (RuSixGe1-x) for an increasing molar fraction of Si atom from 0.0 to 1.0 by 0.1. For each x composition, we have investigated formation energies of different compositions under three different pressure to study the alloying effects on the stability of RuGe in the B2 structure. It was determined that our calculated lattice parameters were in good agreement with the experimental results and decreased with Si content. The band structures and partial density of states (PDOS) have been investigated as electronic property. Using calculated second-order elastic constants, mechanical properties have been obtained for all x compositions. Among the different compositions for RuSixGe1-x under pressure it has been found that the most stable alloys have been obtained for x = 0.9, 0.7, and 0.6 under 0 GPa, 30 GPa, and 60 GPa, respectively. Elastic and dynamical stabilities were confirmed by Born Stability Criteria and positive phonon dispersion curves. Also, the elastic anisotropy has been visualized in detail by plotting the directional dependence of compressibility, Poisson ratio, Young's, and Shear module.

Electron–phonon coupling of the Ti3Sb compound

Using the first-principles method based on density functional theory, we investigate the electronic, mechanical, phononic, superconducting, and topological properties of the A15 superconductor Ti3Sb with/without the inclusion of spin–orbit coupling (SOC). We find that the calculated elastic constants satisfy the Born stability criteria and the ductile nature of Ti3Sb. The result of phonon calculations reveals that the Pm3¯n structure is dynamically stable. Sb atoms are dominated in the low-frequency region due to the mass difference between Ti and Sb from partial phonon calculations. Our electronic structure calculations show that Ti3Sb has metallic band structures with Ti-d bands near the Fermi energy. The electron–phonon coupling constant (λ≃0.80) indicates that Ti3Sb has strong electron–phonon coupling. The critical temperature (Tcμ⋆=0.10) is found to be 6.24 and 6.56 K with and without the SOC effect, respectively. Due to Ti’s relatively small SOC strength, we do not find evidence of non-trivial topology in contrast to Ta compounds such as Ta3Sb.

Lightweight alkali-induced lattice-dynamical stability and energy storage mechanism of quaternary Mg-based hydrides under pressure effect

New-discovery compositions of the lightweight quaternary Mg-based hydrides at ambient pressure are found as NaLiMgH4, NaLiMg2H6, and Na3LiMg4H12, which their stabilities were determined by all positive modes of the phonon dispersion relation. The varying compositions of Na-Li-Mg-H were analyzed using the ab initio random structure searching technique and affirmed by mechanical stability and Born stability criteria. Besides, the effects of pressure on stable structures are considered also. High-gravimetric hydrogen capacity introduces us to study H-vacancy occurrence and H-diffusion kinetics in these lightweight quaternary hydrides. Our calculation results indicated that the NaLiMg2H6 in the P21/m system gave more suitable for hydrogen storage material due to lower energy barriers as well as the hydrogen diffusion kinetics in this lightweight hydride for its practical use in energy storage applications.

Computational investigation of half-metallicity in [formula omitted] half-Heusler alloys GeKZ (Z = Ca, Sr) using first-principles calculations

This paper is based on the study of structural, electronic, magnetic, elastic, phonon dynamics and thermodynamic properties of d0 half-Heusler alloys GeKZ (Z = Ca, Sr) using the Density Functional Theory (DFT) approach. The investigation is carried out using the spin-polarized calculations with pseudopotential approach using Generalized Gradient Approximation by Perdew–Burke–Ernzerhof (GGA-PBE). Both the compounds GeKCa and GeKSr are found to be structurally stable in the ferromagnetic α-phase. The electronic properties in the form of spin-polarized band-structures and density of states of the compounds GeKCa and GeKSr show that they are half-metallic in nature with a finite and large half-metallic band-gap of 0.37 eV and 0.29 eV respectively in the spin-up states and a metallic behavior in the spin-down states with 100 % spin-polarization at the Fermi-level. Integral magnetic moment of 1.00 μB is obtained for both the compounds which is in accordance with the Slater–Pauling Rule for half-Heusler alloys. The elastic properties show that the compounds are mechanically stable following Born stability criteria for cubic compounds and are found to be ductile in nature. The compounds have also been found to be dynamically stable against lattice vibrations on the basis of phonon dispersion calculations. They have also been explored regarding their thermodynamic properties using the quasi-harmonic approximation. They are also examined for the preservation of the integral magnetic moment against the lattice compression and expansion. The observed properties points towards the suitability of these compounds in the spintronics applications.

Equiatomic quaternary CoXCrAl (X = V, Nb, and Ta) Heusler compounds: Insights from DFT calculations

The half-metallic ferromagnets are likely materials to the spintronics systems for the next generation electronic devices. Among the half-metallic ferromagnetic materials, the equiatomic quaternary Heusler (EQH) compounds get great attention in the recent times. In this study, the EQH CoXCrAl (X = V, Nb, and Ta) compounds are investigated using Density Functional Theory (DFT). The three structural types as type-I, type-II, and type-III, are considered to determine the most stable structural types of CoXCrAl compounds. Furthermore, the three magnetic configurations as paramagnetic (PM), ferromagnetic (FM), and antiferromagnetic (AFM), are studied to find out the most stable magnetic configuration. The type-I FM configuration is the most stable configuration for the CoXCrAl compounds. The calculated electronic band structures reveal that the CoXCrAl compounds are half-metals with metallic behavior in spin-up channel and semiconducting behavior in spin-down channel. Also, the possible d-d hybridizations between the Co, X, and Cr atoms are investigated to show the half-metallic character in detail. Furthermore, the calculated elastic constants satisfy the Born stability criteria, then the CoXCrAl compounds have mechanical stability. Using the determined constants, the mechanical properties are obtained for CoXCrAl compounds. In addition, the dynamical properties are studied and it is found that CoXCrAl compounds are dynamically stable. The structural, magnetic, electronic, mechanic and dynamical properties of CoXCrAl compounds that are the potential candidates for the spintronics applications are presented in this study.

Alkaline-Earth Metal Effects on Physical Properties of Ferromagnetic AVO3 (A = Ba, Sr, Ca, and Mg): Density Functional Theory Insights.

The effects of alkaline-earth metals on electronic, optical, thermodynamic, and physical properties of ferromagnetic AVO3 (A = Ba, Sr, Ca, and Mg) have been investigated by first-principles calculations within the GGA+U formalism based on density functional theory. The optimized structural parameters are in good agreement with the available experimental results that evaluate the reliability of our calculations. The cell and mechanical stability is discussed using the formation energy and Born stability criteria, respectively. The mechanical behaviors of AVO3 are discussed on the basis of the results of elastic constants, elastic moduli, Peierls stress, and Vickers hardness. The nature of the ductile–brittle transition of AVO3 compounds was confirmed by the values of Pugh’s ratio, Poisson’s ratio, and Cauchy pressure. The electronic band structures, as well as density of states, reveal the half-metallic behavior of BaVO3 and SrVO3. However, CaVO3 and MgVO3 exhibit spin-gapless and magnetic semiconductor characteristics, respectively. The microscopic origin of the transition from the half-metallic to semiconductor nature of AVO3 is rationalized using electronic properties. The presence of covalent, ionic, and metallic bonds in AVO3 compounds is found by the analysis of bonding properties. The single-band nature of half-metallic AVO3 is seen by observing hole-like Fermi surfaces in this study. Furthermore, the various thermodynamic and optical properties are calculated and analyzed. The refractive index suggests that AVO3 could be a potential candidate for applications to high-density optical data storage devices.

Probing the electronic, optical and transport properties of halide double perovskites Rb2InSb(Cl,Br)6 for solar cells and thermoelectric applications

Halide-based double perovskites have recently been promoted as high-performing semiconductors for photovoltaic and thermoelectricity applications owing to their outstanding efficiency, non-toxicity and ecological stability. In the framework of this research, we have systematically investigated the structural, mechanical, electronic, optical, and thermoelectric properties of Rb2InSb(Cl,Br)6 double halide perovskites. Based on Born stability and tolerance factor criteria, we have found that Rb2InSb(Cl,Br)6 are mechanically and structurally stable. Furthermore, we have performed a comprehensive evaluation of the electronic, optoelectronic, and thermoelectric characteristics. From the electronic band structure results, Rb2InSbCl6 and Rb2InSbBr6 exhibit direct semiconducting band gaps of 1.41 ​eV and 0.53 ​eV, respectively. The optical parameters of Rb2InSb(Cl,Br)6 reveal that our active structures have a higher dielectric constant, with maximum absorption in the visible range reaching over 5.68 ​× ​105 ​cm−1 and high optical conductivity (2.19 fs−1 for Rb2InSbCl6 and 2.14 fs−1 for Rb2InSbCl6). Moreover, the maximum limited spectroscopic efficiency reaches an impressive value of approximately 28.0% for Rb2InSbBr6 and 33.7% for Rb2InSbCl6. The thermoelectric properties were accurately calculated using the BoltzTraP simulation package. The obtained results reveal a significant electrical conductivity, a strong Seebeck coefficient (S ​≈ ​2756 μVK−1 ​at 300 ​K), and an average figure of merit close to one for both structures (ZT ​≈ ​1). Our findings suggest the versatility of these materials and could be used for a wide range of applications, including commercial solar cells and thermoelectricity.

Tuning of the bandgap of Rb2ScAgX6 (X = Cl, Br, I) double perovskites through halide ion replacement for solar cell applications

Double perovskite halides are a potential candidate for the applications of the solar cell, photovoltaic and thermoelectric, due to their non-toxicity and environmental stability. The density functional theory (DFT) calculation investigates the details physical properties of halides Rb2ScAgX6(X = Cl, Br, I) that can be useful for applications like thermoelectric and solar cells. The structural and thermodynamics stability is endorsed by the formation energy, tolerance factor, and Born stability criteria. The calculated indirect band gaps of 1.95 eV, 1.85, and 1.60 eV for Rb2ScAgCl6, Rb2ScAgBr6, and Rb2ScAgI6 respectively, ensure the light absorption in the region of visible range. Therefore, all studied halides are widely used in optoelectronic devices like solar cells. In addition, thermoelectric properties are examined through thermal conductivity, electrical conductivity, and the Seebeck coefficient. ZT values of 0.74, 0.71, and 0.72 for Rb2ScAgI6, Rb2ScAgBr6, and Rb2ScAgCl6 double perovskites are recorded, which spotlight their significance for the applications of thermoelectric.

Piezo‐elasticity and stability limits of monocrystal methane gas hydrates: Atomistic‐continuum characterization

AbstractGas hydrates are guest‐host crystalline materials formed by water cages and guest gases such as methane and carbon dioxide under simultaneously relative high‐pressure and low‐temperature conditions. With this unique guest‐host structural feature, gas hydrates can be used for gas storage and carbon dioxide (CO2) sequestration, creating challenges such as flow assurance and geological stability. Some of these challenges are related to material instabilities caused by changing external conditions. Thus, this paper aims to determine the theoretical pressure stability limits of monocrystal defect‐free sI methane gas hydrates at 0 K using accurate density functional theory to simulate the hydrate's thermodynamic and elastic responses under varying pressures. The pressure stability limits are determined by Born stability criteria and piezo sensitivity factors. The important brittle‐to‐ductile transitions of gas hydrates are established. Also, polycrystalline mechanical properties, including the Poisson ratio and Young modulus, are calculated from the second‐order elastic constants obtained from the monocrystal sI methane hydrates, which provide the upper bounds. Taken together, the piezo‐sensitivity of a complete set of elastic properties of sI methane gas hydrates and material stability limits determined by atomistic calculations provide new data and fundamental understanding for technological applications.

A computational study for mechanical, thermoelectric and optoelectronic applications of BiAlO3 under static pressure

Inorganic perovskites have a wide area of applications in low-cost optical and thermal applications. This manuscript aims to present Structural, mechanical, electronic, optical, as well as thermoelectric behavior of perovskite compounds BiAlO3 (BAO) for optoelectronic as well as thermoelectric applications, a novel energy production mechanism under high static pressure. Thermal stability is computed by enthalpy relation and also confirmed by elastic moduli. Physical properties are measured at ground state energy, and also explored pressure impact up to 100 GPa on electronic structure of BiAlO3. BAO shows an indirect band gap at 0–30 GPa, while it transforms to a direct with an increase in pressure. Mechanical stability was confirmed by applying Born's stability criteria. Even at higher pressure it remains in cubic phase and show mechanically stable structure. Optical responses are calculated and compared under pressure. With an increase in pressure, a clear blue shift was observed. The refractive index of refraction showed a decreasing trend from 3.32 to 2.84 from o to 100 GPa, respectively. Thermoelectric properties are explored by computing electric and thermal conductivity, Seebeck coefficient and power factor. The efficiency of the devices depends upon the figure of merit (ZT) i.e. the ratio of electrical to thermal conductivity must be small. The figure of merit indicated that at low temperature (lower than room temperature and normal pressure) the ZT can reach 0.7, if at high pressure, it can be larger than 0.8. Promising results of thermoelectric response under stress indicate that the said material is suitable for thermoelectric properties. BAO is not only led free but also environment friendly thus, the eventual candidate for devices based on optoelectronics and thermoelectric applications due to relevant bandgap nature after asserting pressure and its thermoelectric nature.

Ab-initio calculation of electronic, mechanical, optical and phonon properties of ZrXH3(X = Co, Ni and Cu): A key towards potential hydrogen storage materials

Hydrogen storage is attractive in research interests due to clean, renewable and green energy properties of hydrogen. Therefore, frequently research studies are carried out to find suitable and innovative materials that fulfill the criteria of hydrogen storage materials. First-principles calculations of ZrXH3([Formula: see text], Ni and Cu) compounds are carried out to find their hydrogen storage properties by using CASTEP code. Structural, mechanical, electronic and optical properties of these materials have been studied. Gravimetric hydrogen storage densities of these materials are also calculated. Electronic properties of these hydrides are also discussed which show the metallic nature of these hydrides. Moreover, mechanical properties identified through elastic constants proved their mechanical stability by satisfying Born stability criteria. Bulk, shear, Young’s moduli, Poisson’s ratio and Vickers hardness show that these three compounds are hard, ductile and have good resistance toward change. We have also calculated the phonon dispersion curves and phonon density of states by using density functional perturbation theory.

Probing direct bandgap of double perovskites Rb2LiTlX6 (X = Cl, Br) and optoelectronic characteristics for Solar cell applications: DFT calculations

A fascinating novelclass of double perovskites materials with interesting optoelectronic and transport features have been discovered. In the current study, optoelectronics and the transport properties of Rb2LiTlX6 (X = Cl, Br) were comprehensively examined. Structure stability was confirmed by calculating tolerance factor value and Born stability criteria. At the Γ-symmetry point, direct band gaps of 2.90 eV and 1.66 eV are observed, ensuring spectral response throughout ultra-violet to visible areas and used as potential candidates for solar cell applications. These are excellent compounds for optoelectronic applications because of their low scattering of light, refractive index range approximately from 1.5 to 2, and wide absorption band in visible areas. Furthermore, thermal properties with the name electrical conductivity, thermal conductivity, Seebeck coefficient, power factor, and figure of merits of double perovskites were studied. The figure of merits (ZT) values of both compounds are 0.43, and 0.51 at room temperature, which confirms that these materials are suitable for use in thermal devices.