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In this study CoZrMnSb, a quaternary Heusler alloy has been explored utilizing the density functional theory based simulation package WIEN2k. The structural analysis exhibits an X1-type structure with a relaxed lattice constant of 6.27 Å in ferromagnetic phase. The band structure calculations show its half-metallic nature with full spin polarization states around the Fermi level at 0.56 eV energy. In addition, the magnetic moment is calculated to be 1.0 μB, which is in accordance with the Slater Pauling rule (Mtot = (Ztot–24) μB). The study shows the d-d hybridization of the transition metals Co, Zr, and Mn elements. Further, optoelectronic performances in terms of dielectric function, reflectivity, energy loss function, absorption coefficient have been determined for a range of photon energy up to12 eV (ultraviolet region). In optoelectronic applications, absorption of this material in visible light enhances its significance. The thermoelectric properties with chemical potential and thermodynamic properties in the pressure range of 0–40 GPa and temperature range of 0–1200 K have been analysed. Specific heat capacity and Debye temperature authenticate similar metallic behaviour of CoZrMnSb alloy at temperature versus pressure variations. At room temperature, the chemical potential study suggests high figure of merit ~ 0.9, which makes it a potential thermoelectric material. The suggested material has a high Seebeck coefficient and low thermal conductivity, making it a better match for waste heat recovery and spintronic applications. [ABSTRACT FROM AUTHOR]

Summary: The structural, electronic, magnetic, mechanical and thermodynamic properties of the Mn2PtCo Heusler alloy have been investigated in the frame work of density functional theory (DFT). The cohesive energies confirm the Cu2MnAl‐prototype structure of Mn2PtCo with the ferromagnetic phase. The spin polarized electronic band profile of the Mn2PtCo exhibits its metallic character by considering the generalized gradient approximation (GGA) and modified Becke‐Johnson (GGA‐mBJ) approximation in the calculations. The magnetic moment is calculated to ~9 μB and it is in accordance with the Slater‐Pauling rule. From the analysis of mechanical properties the brittle nature is anticipated. Further to seek the applications of Mn2PtCo in device fabrication, the thermodynamic properties like entropy, heat capacity at constant volume, Debye temperature, Gruneisen parameter and thermal expansion coefficient within the temperature and pressure range of 0 to 1000 K and 0 to 24 GPa, respectively have also been estimated. [ABSTRACT FROM AUTHOR]

• Quantum mechanical modeling using WIEN2K code. • Predicted various thermodynamic variables under high temperature and pressure. • Structure optimization of BeX (X=Ag, Au) intermetallics in Pm-3m structure. • Predicted elastic and mechanical properties. • Anharmonicity in the crystal reported. The present work reports thermodynamics of BeX(X = Ag, Au) intermetallics in terms of their unit cell volume, bulk moduli, molar heat capacity at constant volume, Gruneisen parameter, thermal expansion coefficient and Debye temperature using a computational quantum mechanical modeling in the frame work of Density-functional theory (DFT). The thermodynamic parameters were studied under temperature range of 0–1200 K and pressure range of 0–40 GPa. The molar heat capacity at constant volume for the considered intermetallics followed Debye T3 law and Dulong-Petit limit was achieved at certain temperature. Further, to understand the highest modes of vibrations in the materials, Debye temperatures for BeAg and BeAu were estimated as 430 K and 335 K, respectively at 0 K and 0 GPa. Furthermore, the thermal expansion coefficient described the dependence of expansion and contraction of the materials on changing temperature, depicting the strength of atomic bonding. Its high value indicated weak atomic bonding, which led to the low melting temperature in the solids. [ABSTRACT FROM AUTHOR]

The mechanical and thermodynamic results of some terbium chalcogenides, TbX (X = S, Se) compounds have been examined using full-potential linear augmented plane wave (FP-LAPW) method based on density functional theory. The local spin density approximation with Hubbard potential (LSDA+U) has been used for proper treatment of 4f-electrons of Tb. The magnetic moment of TbS and TbSe was calculated to be 5.44μB and 5.57μB, respectively. The ground state properties such as lattice parameter, bulk modulus, and pressure derivative of bulk modulus were obtained and found in good agreement with already available theory and experiment results. The mechanical properties such as Young modulus (E), shear modulus (G), Poisson ratio (υ), Cauchy pressure and B/G ratio were also predicted. Further, in thermodynamic properties, Debye temperatures (θD), specific heats at constant volume(CV), thermal expansion co-efficient (α), and entropies (S) and their behavior with high temperature(0–1200 K) and pressure (0–50 GPa) were also predicted. [ABSTRACT FROM AUTHOR]

[Display omitted] • L2 1 structure is stable structure for Rh 2 XZn (X = Mn, Fe). • Rh 2 XZn (X = Mn, Fe) are ferromagnetic in nature with 3.12 & 4.6 µ B , magnetic moments. • Low values of thermal conductivity which is accountable for figure of merit. • Predicted ZT for energy based applications. • High values of Debye temperature for the considered materials. Rh 2 XZn (X = Mn, Zn), full-Heusler compounds have been investigated with respect to their transport and thermodynamic properties using the first-principles approach. The full potential linearized augmented plane wave method with different exchange potentials is used to find the structural stability within considered L2 1 and XA structures. Moreover, Rh 2 XZn (X = Fe, Zn) are found to be ferromagnetic with magnetic moments of ∼3 and ∼4µ B , which are compatible with the Pauling-Slater rule. To further seek the application of the material in the transport phenomena, figure of merit has been estimated by using Boltzmann theory. Our calculations lead to a 0.15 value of figure of merit at 1200 K for Rh 2 FeZn. Furthermore, the thermodynamic stability has been examined by considering various parameters within 0 to 1200 K temperature range. One of the novelties lies within the high value of Debye temperature that surmised the materials to be used as hard materials. [ABSTRACT FROM AUTHOR]

• DFT calculations on ferromagnetic Mn2CoCr with GGA and mBJ approximations. • Predicted specific heat at constant volume and approaches to Dulong-Petit limit. • Mn 2 CoCr is new material exhibits good thermoelectric properties. • Seebeck coefficient, thermal conductivity, power factor calculated for the first time. • Prediction on Debye temperature and thermal expansion coefficient. Heusler compounds have been promising materials for their applications in spintronic, memory and thermoelectric devices. The Mn 2 CoCr, a full Heusler compound, has been investigated here for its mechanical, thermodynamic and thermoelectric prospective for the first time using full potential linearized augmented plane wave (FP-LAPW) method in support of density functional theory (DFT). The estimation of total energy conferred to Fm-3m structure in ferromagnetic phase, which was in accordance to the others finding. The estimated total magnetic moment was found to be 5.02 (in the units of Bohr magneton), which was in accordance with the Pauling-Slater rule and available data. The electronic structure using generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) revealed its metallic nature in both the spin configurations. Further, we have calculated the thermodynamic and thermoelectric constants such as specific heat, Debye temperature, Gruneisen constant, thermal conductivity, Seebeck coefficient and power factor. Our predicted value of specific heat at constant volume is 66.6 J/mol.K at 300 K and 0 GPa, which at higher temperature (1000 K) followed Dulong-Petit limit. The power factor was calculated to be 25x1012 Wm-1K−2 at 500 K, demonstrating its suitability in thermoelectric applications. [ABSTRACT FROM AUTHOR]

• Type-I structure is stable structure for both FeCrTiZ (Z = Si, Ge) compounds. • Ferromagnetic nature results from integer magnetic moment values. • Direct band gap in spin-up of FeCrTiSi. • Indirect band gap in spin-up of FeCrTiGe. • High value of bulk modulus and Debye temperature. • High values of figure of merit which is accountable for thermoelectric generators. The objective of this work is to find the possible applications of the compounds as thermoelectric materials or alternate energy materials. In this regard, FeCrTiZ (Z = Si, Ge) quaternary Heusler compounds have been analyzed via investigating their stable structure and other physical properties by using comprehensive density functional theory executed in the WIEN2k package. The optimized lattice constants and other ground state parameters are found to be concurrent with the existing data. The spin-embraced electronic properties lead to the half-metallic character of the compounds on account of different behavior of the two spins. The obtained total magnetic moment ideally follows the Pauling-Slater rule and is also congruent to the available data. Furthermore, to study the lattice vibrational properties, the dependence of unit cell volume, bulk modulus, Debye temperature, and Gruneisen constant has been estimated within a certain temperature and pressure range by employing a Debye model of quasi-harmonic approximation. The thermoelectric parameters have also been estimated by employing the BoltzTrap code which gives significant values of the figure of merit for both compounds. [ABSTRACT FROM AUTHOR]

In the present study, structural, electronic, optical, thermodynamic and thermoelectric properties of perovskites TlSiF 3 are explored using first-principles calculations based on density functional theory with different exchange-correlation approximations (LDA, PBE-GGA, WC-GGA, PBE-sol GGA, and mBJ-GGA). The computed structure, electronic and charge density plots using PBE-GGA ​+ ​TB-mBJ approximation show that TlSiF 3 is an indirect band gap semiconductor (1.73 ​eV gap along with R– M direction) having ionic and covalent bonding. The optical response is analysed and explained in terms of dielectric function, refractive index, extinction coefficient, optical conductivity, reflectivity, and absorption coefficient in the energy range from 0 to 10 ​eV. The thermoelectric transport behaviour of TlSiF 3 is computed as a function of temperature and chemical potential, μ − E F. Further, the thermoelectric transport behavior of TlSiF 3 is computed as a function of temperature and chemical potential μ − E F (eV). It has been observed that highest value of ZT (0.43) is attained at 1000 ​K with a power factor (PF) of 9.3 ​× ​1010WK−2m−1s−1for a fixed chemical potential. Under varying chemical potential at 300K in n-type region, it exhibits ZT value of 0.98, which is required for thermoelectric devices. Furthermore, pressure as well as temperature dependence of the thermodynamic parameters like Debye temperature, heat capacity, bulk modulus, thermal expansion coefficient, heat capacity, have been estimated with the help of GIBBS program based on quasi-harmonic Debye model. The structural properties of TlSiF 3 compound were determined and we assessed the thin-film photovoltaic efficiency of about 28.5%, and noticed as a promising absorbing material for solar cell device. The optimal value of ZT obtained for this compound is 0.44 ​at 1000K indicating the possibility of TlSiF 3 as an excellent material for thermoelectric applications at high temperature. [Display omitted] • The perovskite TlSiF 3 is explored using FP-LAPW method with different exchange correlation functional. • The computed electronic structure using TB-mBJ approximation show that TlSiF 3 is an indirect band gap(1.729) • The optical response advocated maximum absorption inthe visible region. • The estimated power factor reveals that at optimal charge carriers, n-type TlSiF 3 has a higher power factorof 1.60 ​× ​1010W/K2ms. • The thermodynamic properties are computed based on quasi-harmonic Debye model. [ABSTRACT FROM AUTHOR]