First-principles study of structural, elastic, electronic and optical properties of perovskites XCaH 3 (X = Cs and Rb) under pressure (original) (raw)
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Solid State Communications, 2010
The structural, elastic, electronic, optical and thermodynamic properties of the perovskite chloride CsCdCl3 were investigated using the pseudo-potential plane wave (PP-PW) within the Generalized Gradient Approximation (GGA) and Local Density Approximation (LDA). The computed lattice parameter agrees well with experimental and previous theoretical works. Based on the elastic constants and their related parameters, the crystal rigidity and mechanical stability have been discussed. Energy band structure shows that the investigated material is Γ–R indirect energy band gap semiconductor. The static dielectric constant and static refractive index are indeed, proportional to the fundamental indirect band gap. The thermal effect on the lattice parameter, bulk modulus, volume expansion coefficient, Grüneisen parameter, heat capacities and Debye temperature were predicted using the quasi-harmonic Debye model. To the best of the authors’ knowledge, most of the studied properties are reported for the first time.
Structural, elastic, electronic, and optical properties of cubic perovskite CsCaCl3 are calculated using the full-potential linearized augmented plane wave method in the density functional theory. The exchange-correlation potential is evaluated using the local density approximation and generalized gradient approximation. Further, the modi ed BeckeJohnson potential is also applied for studying the electronic and optical properties. The calculated structural properties such as equilibrium lattice constant, the bulk modulus and its pressure derivative are in good agreement with the available data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are calculated. The calculations of electronic band structure, density of states and charge density show that this compound has an indirect energy band gap (M) with a mixed ionic and covalent bonding. Calculations of the optical spectra such as the real and imaginary parts of dielectric function, optical re ectivity, absorption coe cient, optical conductivity, refractive index, extinction coe cient and electron energy loss are performed for the energy range of 030 eV. Most of the studied properties are reported for the rst time for CsCaCl3.
RSC Advances, 2023
This study communicates the theoretical investigations on the cubic double perovskite compounds Cs 2 XCrCl 6 (X = K or Na). Density functional theory (DFT) calculations were carried out using the TB-mBJ approximation. These compounds were found to be stable in the cubic perovskite structure having lattice constants in the range of 10.58-10.20. The stability of the investigated materials was assessed by the Gold-Schmidt tolerance method, which resulted in the tolerance factor values of 0.891 and 0.951 for Cs 2 KCrCl 6 and Cs 2 NaCrCl 6 , respectively. The calculated values of the elastic constants C 11 , C 12 , and C 44 of the cubic compounds studied by our research team confirm the elastic stability. The values of the formation energies were also calculated for both the compounds and were found in the range from −2.1 to −2.3. The electronic behavior of the presently investigated materials was examined by inspecting their band structures and the density of states. It was observed that both the materials have half-metallic nature. To check the suitability of the studied compounds in optical applications, we determined the real and imaginary parts of their respective dielectric functions, absorption coefficients, optical conductivities, refractive index, and reflectivity as a function of a wide range of incident photon energies up to 40 eV.
Physica B-condensed Matter, 2023
Structural, optical and electronic properties and elastic constants of Cd1-x-y Zn x Hg y Te alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers-Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard's law. It is seen that results obtained from theory and experiments are all in agreement.
Social Science Research Network, 2022
Structural, optical and electronic properties and elastic constants of Cd1-x-y Zn x Hg y Te alloys have been studied by employing the commercial code Castep based on density functional theory. The generalized gradient approximation and local density approximation were utilized as exchange correlation. Using elastic constants for compounds, bulk modulus, band gap, Fermi energy and Kramers-Kronig relations, dielectric constants and the refractive index have been found through calculations. Apart from these, X-ray measurements revealed elastic constants and Vegard's law. It is seen that results obtained from theory and experiments are all in agreement.
Structural and electronic properties of perovskite hydrides ACaH3 (A=Cs and Rb)
BIBECHANA, 2015
We have performed structural properties, electronic properties, charge density and potential distribution of CsCaH3 and RbCaH3 using TB-LMTO-ASA approach under local density approximation. Our findings show that both CsCaH3 and RbCaH3 are non-magnetic and then insulators with estimated direct band gaps (M-M) of 3.15 eV and 3.17 eV respectively. Our estimated values of band gap suggest to both materials as better candidate for the high frequency ultra-violet devices. Furthermore, role of corner atoms in perovskite hydrides are also presented in this study. Present calculations agree well with the previous work.BIBECHANA 13 (2016) 94-99
Effect of pressure on the global and local properties of cubic perovskite crystals
Physica Scripta, 2011
The influence of pressure on the structural, elastic, thermal and bonding properties of four perovskite-type oxides AMO 3 is studied from the point of view of the quantum theory of atoms in molecules. Ab initio investigations are performed by means of the full-potential linear augmented plane-wave method as implemented in the wien2k code. The integrated basin charges resulting from the topological analysis of electronic density provide a partition of the bulk modulus and compressibility into atomic contributions. Special attention is paid to the nonlinear behaviour of the local bonding properties. PACS numbers: 71.15.Mb, 71.15.−m, 62.20.de, 31.15.ae (Some figures in this article are in colour only in the electronic version.)
Recent energy deficits have influenced an intensification of demand for renewable energy sources. The utilization of these energy sources necessitates the availability of substances that possess the capability of absorbing visible wavelengths of light. The electronic and optical properties, along with the structure stability of Rb 2 NaScCl 6 , a double perovskite devoid of toxicity, were determined in our study. The DFT calculation utilizing the WIEN2k program is implemented in our study. The stability and legality of the structure being an ideal cubic symmetry along with space group Fm3m have been determined through the utilisation of the tolerance factor and octahedral factor. The precise value for the band-gap is identified as being 3.9 electron volts, while the absorption coefficient has been observed to fall within the ultraviolet range. The compound's simulated properties were analysed under different pressure conditions. Both electronic and optical properties shows a significant change under different pressure. The results show that the band-gap got broader up to 20 GPa, but then it started to get smaller as the pressure went up. Additionally, there was a shift in absorption from the ultraviolet to visible range of wave length as pressure increased over 20 GPa. With appropriate modification, the material exhibits promising potential for utilization in diverse sectors, particularly in the realm of new energy production applications.