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The perovskite material, lithium lanthanum titanate Li 3x La 2/3-x TiO 3 (LLTO) is one of the interesting prospects that may be employed as a solid-state inorganic electrolyte for Li-ion batteries. Here, three various formulations corresponding to: (i) 3x = 0.1 (Li 0.1 La 0.63 TiO 3), (ii) 3x = 0.3 (Li 0.3 La 0.57 TiO 3), and (iii) 3x = 0.5 (Li 0.5 La 0.5 TiO 3) were synthesized using sol-gel method. The impacts of lithium concentration, calcination temperature, elemental composition, microstructure, optical properties, and conductivity of the ceramics were studied using a plethora of techniques. DFT calculations were performed on Li 0.5 La 0.5 TiO 3 to get an in-depth understanding on the relationship between the structure –electronic– optical properties of LLTO materials. Our results show that the grain and crystallite sizes behave inversely proportional to the band gap. Maximum grain ionic conductivity on the order of 10−3S/cm and grain boundary ionic conductivity on the order of 10−6S/cm were obtained for both samples (3x = 0.3 and 3x = 0.5) at higher temperatures. The total density of states indicates that the titanium d-bands (Ti-d) and oxygen p–bands (O-p) form covalent Ti-O bond character. The formation of localized states is suggested to result in the lowering of the band gap energy, when lithium content is increased. Finally, the calculated mechanical properties show that LLTO (3x = 0.5) possess high elastic moduli as compared to other solid electrolytes. [ABSTRACT FROM AUTHOR]

Herein, a series of perovskite‐type hydride materials RMnH3 (R = Ca, Sr, and Ba) are investigated by density functional theory for solid‐state hydrogen storage. Their structural, mechanical, electronic, and optical properties are calculated and their thermodynamic, dynamic, and mechanical stability is assessed. All compounds crystallize in the undistorted cubic perovskite system with the Pm‐3m symmetry. The results from mechanical properties, based on parameters such as Poisson's ratio (ν) and the G/B ratio, indicate that CaMnH3 and SrMnH3 exhibit brittle behavior, primarily attributed to the dominance of ionic bonds, while BaMnH3 is distinguished by its ductility, resulting from a prevalence of covalent bonds. Additionally, the electronic structure analysis reveals that all examined hydrides possess metallic behavior. Further calculations of the optical properties are also performed, providing supplementary insights into the physical features of the hydrides. The gravimetric hydrogen storage capacities (Cwt%) are calculated, with values of 2.96 wt% for CaMnH3, 2.019 wt% for SrMnH3, and 1.513 wt% for BaMnH3, accompanied by respective desorption temperatures of 214.83, 193.42, and 145.43 K. Overall, these results highlight the potential of perovskite hydrides RMnH3 as promising materials for hydrogen storage applications, significantly contributing to a sustainable energy future. [ABSTRACT FROM AUTHOR]

The following work presents a theoretical study on new quaternary Heusler compounds called TaAlCuCo under varying pressures from 0 to 100 GPa. The study comprehensively investigates the material's structural, elastic, mechanical, electronic, optical, and vibrational properties. The results reveal that as the applied pressure increases, the lattice parameters of TaAlCuCo decrease from 6.058465 to 5.476836 Å. Furthermore, the material exhibits desirable characteristics such as ductility, metallic bonding, and stability even under high pressure. Notably, TaAlCuCo demonstrates anisotropic behavior, indicating that its properties vary depending on the measurement direction. The study also observes a widening of the material's bandgap from 0.010 to 0.333 eV with increasing pressure, suggesting a decline in conductivity. Additionally, TaAlCuCo exhibits favorable optical properties, including a high refractive index, absorption, reflectivity, and conductivity, thereby indicating its potential as a UV filter and for use optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this work, we explore the physical properties of RbXH3 (X=Cr, Zr) perovskite hydrides for solid‐state hydrogen storage. The structural, mechanical, electronic, optical, and hydrogen storage properties were theoretically investigated using density functional theory and CASTEP software. The selected candidates were fully relaxed and optimized in the cubic phase space group Pm‐3 m. The structural phase stability was verified by means of thermodynamic, dynamic and mechanical stabilities. Mechanical analyses based on Poisson's ratio (ν), G/B ratio, and Cauchy pressure show that RbCrH3 and RbZrH3 exhibit brittle behavior with preference of ionic bonding. The electronic structures unveil half‐metallicity in RbCrH3 compound and metallic‐like behavior in RbZrH3. Furthermore, optical calculations were also conducted to gain additional insights into the physical properties of RbXH3 compounds. The gravimetric hydrogen storage (Cwt %) capacities have been calculated as 2.09 wt % and 1.64 wt % for RbCrH3 and RbZrH3, respectively. The hydrogen desorption temperatures have been obtained as 545.11 K and 548.15 K for RbCrH3 and RbZrH3, respectively. Our calculation propose RbCrH3 hydride as potential material for hydrogen storage application. [ABSTRACT FROM AUTHOR]

The exploration of perovskite compounds incorporating actinide and divalent elements reveals remarkable characteristics. Focusing on PbBkO3, RaBkO3, and SrBkO3, these materials were studied using density functional theory (DFT) via the CASTEP code to analyze their electronic, optical, and mechanical properties. The results show semiconductor behavior, with respective band gaps of 1.320 eV for PbBkO3, 3.415 eV for RaBkO3, and 2.775 eV for SrBkO3. Additionally, the elastic constants Cij, bulk modulus B, elasticity modulus G, Young's modulus Y, and Poisson's ratio v were optimized, highlighting anisotropic behavior. The mechanical stability of the compounds meets Born's criteria, and RaBkO3 stands out with a stable lattice dynamic, as demonstrated by phonon dispersion curves in the Pm-3 m space group. The optical properties of these materials indicate they are excellent absorbers of incident radiation, suggesting their potential for applications in magnetic sensors due to their anisotropic magnetic behavior, as well as for capturing solar radiation in the ultraviolet range. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two perovskite hydrides are examined for hydrogen storage using DFT. • KXH 3 (X=Mn and Fe) hydrides are mechanically and thermodynamically stable. • KXH 3 perovskites are metallic in nature. • The GHD (Cwt%) of KXH 3 (X=Mn and Fe) is calculated as ∼3.021 and 2.994 wt%. Materials of the perovskite type could be a good option for applications involving the storage of hydrogen. In this work, the structural, electrical, mechanical, hydrogen storage, and thermodynamic characteristics of cubic perovskite-type hydride compounds KXH 3 (X = Mn, Fe) were examined using the density functional theory (DFT). KXH3 compounds have been optimized in cubic crystal structure and the lattice constants have been obtained as 3.8834 Å and 3.7283 Å for KMnH3 and KFeH3, respectively. The structural optimization results show also that both compounds have negative formation energies of −0.722 eV and −0.557 eV for KMnH3 and KFeH3, respectively, indicating their thermodynamic stability. Their mechanical stability was also confirmed through the computation of the elastic constants and other polycrystalline mechanical properties like bulk modulus, Poisson's ratio, etc. Both compositions exhibit metallic behavior, according to the electronic band structure and density of states. Thermodynamic properties, such as entropy, specific heat at constant volume, Grüneisen parameter and Debye temperature were assessed using the quasi-harmonic Debye model over a temperature range of 0 to 1000 K and pressure range of 0 to 25 GPa. These compounds show gravimetric hydrogen storage capacities of 3.021 wt% for KMnH3 and 2.994 wt% for KFeH3, with desorption temperatures of 532.994 K and 411.188 K, respectively. These properties are of considerable interest for solid hydrogen storage materials. [ABSTRACT FROM AUTHOR]

The application requirements of solid-state lithium (Li) metal batteries are satisfied by the ionic conductivity of composite solid-state electrolytes, attributed to their minimal interfacial resistance. Herein, composite solid electrolytes were obtained by mixing a crystalline Li 0.5 La 0.5 TiO 3 (LLTO) perovskite with different amount of 47Li 2 O-30B 2 O 3 -23P 2 O 5 (LBP) glass phase. The results show that the crystal phase of the composite samples exhibit a tetragonal perovskite structure with a P4/mmm space group. Frequency dependent AC conductivity shows that composite containing 1 % LBP glass avoids the phenomenon of charge carrier blocking at low frequency and low temperature at the same time. The room temperature maximum total ionic conductivity was obtained for sample with 0.5 % LBP glass presenting a conductivity that is almost three times higher than that of pure LLTO. The factors influencing ionic conductivity are not only grain morphology and size, and activation energy, but also lithium content, and entropic effects contribute to the facility or difficulty with which Li+ can migrate into the LLTO solid electrolyte. • The composite solid electrolytes were obtained by mixing a crystalline Li 0.5 La 0.5 TiO 3 (LLTO) perovskite with different amount of Li 2 O-B 2 O 3 -P 2 O 5 (LBP) glass. • Modifying grain boundary of LLTO with LBP glass. • AC conductivity shows that composite containing 1 % LBP glass avoids the phenomenon of charge carrier blocking. • The factors influencing ionic conductivity are not only grain morphology and size, and activation energy, but also lithium content, and entropic effects. [ABSTRACT FROM AUTHOR]

The barium titanate Ba 1-x Ce 2x/3 TiO 3 (BCTx, x = 0, 1, 2 and 3 %) have been produced using the sol-gel process. The impact of cerium concentration on structure and optical properties was examined using techniques such as X-ray diffraction, infrared spectroscopy, Raman spectroscopy and UV–visible spectroscopy. DFT calculation were carried out on BCTx to obtain an extensive comprehension of the relationship between the structure and electronic properties of BCTx. The findings demonstrate a tetragonal structure for BCT0 and a pseudo-cubic for the doped samples. The UV–visible study indicates a successive reduction in bandgap due to vacancies in the A site, lattice defect formation and local bond distortion. For every sample, the electronic band structure showed a direct band gap. The partial density of states (PDOS) revealed that the valence band was dominated by the 2p orbitals of the O atoms. However, the conduction band was formed by the 3d orbitals of the Ti atom. [ABSTRACT FROM AUTHOR]