Search Results (29)

The transition toward a sustainable hydrogen economy requires the development of advanced materials capable of efficient hydrogen storage and energy conversion. In this work, we present a comprehensive first-principles investigation of the structural, electronic, elastic, and thermoelectric properties of cubic perovskite hydrides XMoH₃ (X = Na, K, and Rb) using the density functional theory within the generalized gradient approximation combined with the Boltzmann transport theory. The calculated gravimetric hydrogen storage capacities are 2.48 wt%, 2.19 wt%, and 1.64 wt% for NaMoH₃, KMoH₃, and RbMoH₃, respectively, indicating moderate storage potential. Elastic analysis confirms mechanical stability and reveals predominantly brittle-to-intermediate behavior with mixed bonding characteristics. Electronic band structures and density of states demonstrate metallic conductivity, driven mainly by Mo-d orbital contributions near the Fermi level, which may facilitate charge transport and hydrogen mobility. Thermoelectric analysis shows temperature-dependent electrical and thermal conductivities, with KMoH₃ and NaMoH₃ exhibiting relatively higher power factors at elevated temperatures, although the overall figure of merit (ZT < 0.3) remains below the threshold for high-performance thermoelectric applications. Despite these limitations, the combined properties of structural stability, metallic conductivity, and moderate hydrogen storage capacity highlight the potential of XMoH₃ compounds as multifunctional materials for integrated hydrogen storage and thermal energy recovery systems. This study provides fundamental insights into the design of perovskite hydrides and underscores their relevance as tunable platforms for future sustainable energy technologies. Full article

This study provides a theoretical assessment of the structural, electronic, and thermal properties of MgMH₃ (M = Mn and Ni) compounds using the full-potential linearized augmented plane wave (FP-LAPW) method, with a range of modern functionals. The thermoelectric properties that are surveyed here relate to the power factor, the dimensionless thermoelectric figure of merit, the thermal conductivity, and the electrical conductivity that are associated with these compounds. The study finds that MgNiH₃ has superior thermoelectric properties compared to MgMnH₃. The analysis of the band structure reveals that both materials conduct electricity like metals, as there is no energy gap (0 eV), indicating that the conduction and valence bands overlap. The thermal conductivity was found to be linearly related to an increase in temperature, whereas the electrical conductivity varied with temperature. At elevated temperatures, the maximum power factor values reach 1.45 × 10⁻³ W/(K².m) for MgMnH₃ and 1.96 × 10⁻³ W/(K².m) for MgNiH₃ at 900 K. Upon examination of the electronic states, the contributions to the metallic nature of these hydrides come largely from the Ni and Mn orbitals. This type of prospective information on the potential of MgNiH₃ and MgMnH₃ in industrial applications, especially thermoelectric applications, is a valuable contribution. Understanding their thermal and electronic structure will demonstrate their potential for industry. Full article

The current work determines the physical properties of Cs₂HfCl₆ photovoltaic compounds including their structural, electronic, and optical behavior, utilizing the DFT approach. The simulated Cs₂HfCl₆ lattice constants, cell volumes, and bond lengths decrease as the pressure increases from 0 to 20 GPa. The band structure analysis reveals that the calculated under-pressure (0–20 GPa) of Cs₂HfCl₆ is semiconducting with a flexible indirect bandgap (5.44, 2.76, 2.02, 1.45, and 0.99) eV. The electronic bandgap diminishes (0–20 GPa), transitioning the compound from the UV to the visible spectra. This alteration improves the transition from the VBM to the CBM, hence augmenting the optical effectiveness. Concurrently, the dielectric function escalates, enhancing the absorption and conductivity, and causing a red shift in the optical spectra, while diminishing the reflection in the visible spectra. Our findings on the hydraulic pressure (0–20 GPa) and the electrical and optical properties indicate that Cs₂HfCl₆ may be utilized in the development of next-generation solar cells, LEDs, UV sensors, and high-pressure optical instruments. Full article

The aim of this work was to investigate the possibility of doping copper sulfide Cu₂S with selected fifth-group elements, potentially having a positive effect on the thermoelectric properties of the resulting materials. For the selected model structures, theoretical calculations and an analysis of the electronic structure and changes in the enthalpy of formation due to doping were performed using the WIEN2k package employing the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method within density functional theory (DFT) formalism. Polycrystalline materials with the nominal composition of Cu₃₂S₁₅X₁ (X = P, As, Sb, Bi) were synthesized in quartz ampoules, then sintered using the spark plasma sintering (SPS) technique and “SPS melting” method. The chemical and phase compositions of the obtained sinters were studied by X-Ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, investigations of thermoelectric properties, i.e., electrical conductivity, Seebeck coefficient and thermal conductivity in the temperature range 300–920 K, were performed. The results of this study indicate that only phosphorus is successfully incorporated into the Cu₂S structure. Full article

A single crystal of Bi₆Te₂O₁₅ was obtained from the melt of the solid-state reaction of Bi₂O₃ and TeO₃. Bi₆Te₂O₁₅ crystallizes in the Pnma space group (No. 62) and exhibits a three-dimensional network structure with a =10.5831(12) Å, b = 22.694(3) Å, c = 5.3843(6) Å, α = β = γ = 90°, V = 1293.2(3) ų, and Z = 4. The structure was determined using single-crystal X-ray diffraction. An asymmetric unit in the unit cell, Bi₃Te₁O_7.5, uniquely composed of four Bi³⁺ sites, one Te⁶⁺ site, and nine O²⁻ sites, was solved and refined. As a bulk phase, Bi₆Te₂O₁₅ was also synthesized and characterized using powder X-ray diffraction (XRD), infrared (FT-IR) spectrometry, and the thermogravimetric analysis (TGA) method. Through bond valence sum (BVS) calculations from the single crystal structure, Bi and Te cations have +3 and +6 oxidation numbers, respectively. Each Bi³⁺ cation forms a square pyramidal structure with five O²⁻ anions, and a single Te⁶⁺ cation forms a six-coordinated octahedral structure with O²⁻ anions. Since the lone-pair electron (Lp) of the square pyramidal structure, [BiO₅]⁷⁻, where the Bi⁺ cation occupies the center of the square base plane, exists in the opposite direction of the square plane, the asymmetric environments of all four Bi³⁺ cations were analyzed and explored by determining the local dipole moments. In addition, to determine the extent of bond strain and distortion in the unit cell, which is attributed to the asymmetric environments of the Bi³⁺ and Te⁶⁺ cations in Bi₆Te₂O₁₅, bond strain index (BSI) and global instability index (GII) were also calculated. We also investigated the structural, electronic, and optical properties of the structure of Bi₆Te₂O₁₅ using the full potential linear augmented plane wave (FP-LAPW) method and the density functional theory (DFT) with WIEN2k code. In order to study the ground state properties of Bi₆Te₂O₁₅, the theoretical total energies were calculated as a function of reduced volumes and then fitted with the Birch–Murnaghan equation of state (EOS). The band gap energy within the modified Becke–Johnson potential with Tran–Blaha parameterization (TB-mBJ) revealed a value of 3.36 eV, which was higher than the experimental value of 3.29 eV. To explore the optical properties of Bi₆Te₂O₁₅, the real and imaginary parts of the dielectric function, refraction index, optical absorption coefficient, reflectivity, the real part of the optical conductivity extinction function, and the energy loss function were also calculated. Full article

In this theoretical study, the electronic, structural, and optical properties of copper-doped zinc oxide (CZO) were investigated using the full-potential linearized enhanced plane wave method (FP-LAPW) based on the density functional theory (DFT). The Tran–Blaha modified Becke–Johnson exchange potential approximation (TB-mBJ) was employed to enhance the accuracy of the electronic structure description. The introduction of copper atoms as donors in the ZnO resulted in a reduction in the material’s band gap from 2.82 eV to 2.72 eV, indicating enhanced conductivity. This reduction was attributed to the Co-3d intra-band transitions, primarily in the spin-down configuration, leading to increased optical absorption in the visible range. The Fermi level of the pure ZnO shifted towards the conduction band, indicating metal-like characteristics in the CZO. Additionally, the CZO nanowires displayed a significant blue shift in their optical properties, suggesting a change in the energy band structure. These findings not only contribute to a deeper understanding of the CZO’s fundamental properties but also open avenues for its potential applications in optoelectronic and photonic devices, where tailored electronic and optical characteristics are crucial. This study underscores the significance of computational techniques in predicting and understanding the behavior of doped semiconductors, offering valuable insights for the design and development of novel materials for advanced electronic applications. Full article

To examine the structural, optoelectronic, thermodynamic, and thermoelectric properties of KBaTh (Th = Sb, Bi) half-Heuslers, we used the full potential, linearized augmented plane wave (FP_LAPW) approach as in the Wien2K simulator. Generalized gradient approximation (GGA), technique, was used for the structural optimization. Mechanical stability and ductility were inherent characteristics of the studied KBaTh (Th = Sb, Bi). Having band gaps of 1.31 eV and 1.20 eV for the KBaTh (Th = Sb, Bi) compounds, they have a semiconducting character. The KBaTh (Th = Sb, Bi) compounds are suggested for use in optoelectronic devices based on studies of their optical characteristics. Thermoelectric properties were investigated using the Boltzmann transport provided by the BoltzTraP software. Since the acquired figures of merit (ZT) values for the KBaTh (Th = Sb, Bi) compounds are all almost equal to one at room temperature, this demonstrates that these substances can be used in thermoelectric devices. Additionally, we used the Slack method to determine the lattice thermal conductivity of KBaTh (Th = Sb, Bi). Our research shows that the half-Heusler compounds under investigation increase actuator response time and hence can be considered as good materials for actuators. Full article

Modern manufacturing is aiming for products that are readily available, environmentally sustainable, and energy efficient. This paper delves into the exploration of compounds meeting these criteria. Specifically, we investigate the structural, elastic, optoelectronic, and transport properties of XSnBr₃ (X = Rb/Cs) compounds utilizing the full-potential linearized augmented plane wave program (FP LAPW), a component of Wien2K software. Structural optimization is carried out through the generalized gradient approximation (GGA) approach, yielding lattice constants consistent with preceding numerical and experimental studies. The explored XSnBr₃ (X = Rb/Cs) materials exhibit ductility and mechanical stability. Notably, XSnBr₃ (X = Rb/Cs) displays a direct bandgap, signifying its semiconducting nature. The bandgap values, as determined by the modified Becke–Johnson (mBJ) approach, stand at 2.07 eV for X = Rb and 2.14 eV for XSnBr₃ (X = Rb/Cs). Furthermore, utilizing the BoltzTraP software’s transport feature, we investigate thermoelectric properties. Remarkably, XSnBr₃ (X = Rb/Cs) demonstrates impressive figures of merit (ZT) at room temperature, implying its potential to serve as a material for highly efficient thermoelectric devices. This research holds promise for contributing to the development of environmentally friendly and energy-efficient technologies. Full article

The primary objective of contemporary manufacturing is to produce items that are low-cost, environmentally friendly, and energy efficient. This study aimed to investigate compounds that fulfil these criteria, with a focus on CdCrO₃. The full potential linearized augmented plane wave program (FP LAPW), as in Wien2K, was employed to examine the structural, electronic, thermodynamic, and transport characteristics of the material. Structural optimization was carried out using generalized gradient approximation (GGA), with lattice constants that were deemed satisfactory based on previous theoretical and experimental results. Calculations of the magnetic characteristics of CdCrO₃ show that the Cr atoms are principally responsible for magnetism. The quasi-harmonic Debye model allows for the identification of thermodynamic properties including trends, the relative Debye temperature, thermal expansion parameter, relative volume, and heat capacity at various pressures and temperatures. At constant volume, a heat capacity of 52 J/mol K was determined. The thermoelectric properties were examined using the Boltzmann transport offered by the BoltzTrap program. At room temperature, CdCrO₃ had a figure of merit (ZT) value that was almost equal to one, indicating that it may be used to make thermoelectric devices with the highest possible efficiency. Full article

We present a comprehensive study on the structural, electronic, and optical properties of $V_{x}A{l}_{1-x}N$ ternary alloys using first-principles calculations. Our investigations employ the full-potential linearized augmented-plane-wave (FP-LAPW) method within the density functional theory (DFT) framework. The impact of varying vanadium composition (x = 0, 0.25, 0.5, 0.75, 1) on the structural, electronic, and optical characteristics of wurtzite $V_{x}A{l}_{1-x}N$ alloys is examined in detail. Our findings reveal a distinct nonlinear relationship between the lattice constant, bulk modulus, and the concentration of vanadium (x) in the $V_{x}A{l}_{1-x}N$ alloys. An analysis of the electronic band structures and densities of states reveals a metallic behavior in the $V_{x}A{l}_{1-x}N$ alloys, primarily driven by the V-d states near the Fermi energy. These results shed light on the electronic properties of the alloys, contributing to a deeper understanding of their potential for various applications. Furthermore, we calculate various optical properties, including the real and imaginary dielectric functions, refractive index, energy loss spectrum, and reflectivity. The obtained optical functions provide valuable insights into the optical behavior of the $V_{x}A{l}_{1-x}N$ alloys. The results contribute to the fundamental knowledge of these materials and their potential applications in various fields. Full article

This research is being conducted to learn more about various compounds and their potential uses in various fields such as renewable energy, electrical conductivity, the study of optoelectronic properties, the use of light-absorbing materials in photovoltaic device thin-film LEDs, and field effect transistors (FETs). AgZF3 (Z = Sb, Bi) compounds, which are simple, cubic, ternary fluoro-perovskites, are studied using the FP-LAPW and low orbital algorithm, both of which are based on DFT. Structure, elasticity and electrical and optical properties are only some of the many features that can be predicted. The TB-mBJ method is used to analyze several property types. An important finding of this study is an increase in the bulk modulus value after switching Sb to Bi as the metallic cation designated as “Z” demonstrates the stiffness characteristic of a material. The anisotropy and mechanical balance of the underexplored compounds are also revealed. Our compounds are ductile, as evidenced by the calculated Poisson ratio, Cauchy pressure, and Pugh ratio values. Both compounds exhibit indirect band gaps (X-M), with the lowest points of the conduction bands located at the evenness point X and the highest points of the valence bands located at the symmetry point M. The principal peaks in the optical spectrum can be understood in light of the observed electronic structure. Full article

In the current study, the peculiar nonlinear optical (NLO) properties of KAgCh (Ch = S, Se) and their structural, electronic, and thermodynamic properties are computed utilizing the FP-LAPW (full-potential linearized augmented plane wave) approach as embedded in Wein2K code. The Perdew–Burke–Ernzerh of generalized gradient approximation (PBE-GGA) was considered for the structural optimization. The computed bandgaps are found to be 2.57 and 2.39 eV for KAgS and KAgSe, respectively. Besides the structural and electronic properties, we also computed the refractive indices n(ω), surface energy loss function (SELF), and nonlinear optical susceptibilities. The estimated refractive indices, energy band gap, and their frequency dependence for the investigated KAgCh (Ch = S, Se) compounds, along with the NLO coefficients, are found to be in good agreement with the earlier reports. These current findings suggest that KAgCh (Ch = S, Se) can be recommended for nonlinear optical applications in the near-infrared spectrum. Full article

In this article, the structural, elastic, electronic, and magnetic characteristics of both regular and inverse Heusler alloys, Sc₂TiAl and Sc₂TiSi, were investigated using a full-potential, linearized augmented plane-wave (FP-LAPW) method, within the density functional theory. The optimized structural parameters were determined from the minimization of the total energy versus the volume of the unit cell. The band structure and DOS calculations were performed within the generalized gradient approximation (GGA) and modified Becke–Johnson approaches (mBJ-GGA), employed in the Wien2K code. The density of states (DOS) and band structure (BS) indicate the metallic nature of the regular structure of the two compounds. The total spin magnetic moments for the two compounds were consistent with the previous theoretical results. We calculated the elastic properties: bulk moduli, $B$, Poisson’s ratio, $\nu$, shear modulus, S, Young’s modulus (Y), and the B/s ratio. Additionally, we used Blackman’s diagram and Every’s diagram to compare the elastic properties of the studied compounds, whereas Pugh’s and Poisson’s ratios were used in the analysis of the relationship between interatomic bonding type and physical properties. Mechanically, we found that the regular and inverse full-Heusler compounds Sc₂TiAl and Sc₂TiSi were stable. The results agree with previous studies, providing a road map for possible uses in electronic devices. Full article

This work focuses on study of the structural, electronic, thermodynamic and thermoelectric properties of RbNbCd and RbNbZn Half Heusler (HH), utilizing a full-potential linearized augmented plane wave (FP-LAPW) approach and the Boltzmann transport equation using a constant relaxation time approximation within the context of density functional theory (DFT) as embedded in the WIEN2k code. The structural analysis employed the generalized gradient approximation (GGA) and considered the Birch Murnaghan equation of state (EOS), which results in the stable phase for RbNbCd and RbNbZn. The positive phonon spectra indicate the dynamical stability of the studied RbNbCd and RbNbZn. The compounds under investigation that have no bandgap are metallic, as evidenced by their electronic properties. Their mechanical and thermal stability as well as their anisotropic and ductile character are confirmed by the various elastic and thermodynamic parameters. The lattice thermal conductivity has been calculated. This thorough analysis demonstrates the applicability of the studied RbNbCd and RbNbZn for thermoelectric applications. Full article

In this work, the structural, elastic, electronic, thermodynamic, optical, and thermoelectric properties of cubic phase SnTiO₃ employing first-principles calculation are examined. The calculations of all parameters via various potentials such as LDA, PBE-GGA, WC-GGA, PBEsol-GGA, mBJ-GGA, nmBJ-GGA, and HSE are performed. The computed band structure yields an indirect bandgap of 1.88 eV with the HSE approach. The optical parameters have been evaluated through absorption, dispersion, and loss function. For cubic phase SnTiO₃, the maximum absorption coefficient $\alpha \left(\omega \right)$ is 173 × 10⁴ (cm)⁻¹ at high energy region 9 eV. The thermoelectric properties of the SnTiO₃ have been explored by the Seebeck coefficient, thermal conductivity, and power factor employing the BoltzTrap code with temperature and chemical potential. Furthermore, the thermodynamic quantities under high pressure (0–120 GPa) and temperature (0–1200 K) are also calculated. Full article