A FP-LAPW Study on Ground State Electronic Nature of RESn3 (RE= La, Ce, Pr and Nd) Intermetallic Compound

First principles study of structural and electronic properties of non- magnetic LaSn3 and CeSn3 as well as ferromagnetic PrSn3 and NdSn3 rare-earth intermetallic compounds, which crystallize in AuCu3-type structure, is performed using density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. The ground state calculations are carried out within PBE-GGA and LSDA approximations for the exchange correlation potential. Lack of availability of data regarding the above properties of RESn3 motivated us to perform systematic study of these compounds. The ground state properties such as lattice parameter are found to be in good agreement with the available experimental data. The electronic band structure calculations for the studied RESn3 compounds show metallic character in both majority and minority spin channels. Keywords: Rare-earth; Density functional theory; Metallic

Density Functional Calculations on Structural and Elastic Properties of BeCo Intermetallic under Pressure

The structural and elastic properties of beryllium cobalt intermetallic compound in B2-type (CsCl) structure are studied. The calculations were performed employing full potential linearized augmented plane wave (FP-LAPW) method. It is based on density functional theory (DFT). The generalized gradient approximation (GGA) in the scheme of Perdew, Burke and Ernzrhof (PBE) Wu and Cohen (WC) and Perdew et al. (PBE-sol) has been used for the exchange correlation potential. The equilibrium properties such as lattice constant (a0), bulk modulus (B) and its first derivative (B') have been obtained. The calculated equilibrium lattice parameters are in excellent agreement with the available experimental and other theoretical results. We first time report the variation of elastic constants under pressure range (0 GPa - 20 GPa). Keywords: FP-LAPW method, intermetallic compounds, elastic constants, equation of states

Ab-initio Calculations of Structural, Electronic, Elastic and Mechanical Properties of REIn3 and RETl3 (RE= Yb & Lu) Intermetallic Compounds

A theoretical study of structural, electronic and elastic properties of REIn3 and RETl3 (RE = Yb & Lu) intermetallics have been investigated systematically using first principles density functional theory. The calculations are carried out using generalized gradient approximation (PBE-GGA) for the exchange correlation potential. The ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B′) are calculated which show well agreement with the experimental and other available theoretical results. We first time predict elastic constants for these compounds. From energy dispersion curves, it is found that these compounds are metallic in nature. Both of these compounds are found to be ductile in nature in accordance with Pugh’s criteria.. Keywords: Rare-earth; Density functional theory; Elastic constants

Structural, Electronic, Thermal and Elastic Properties of Ductile PdSc and PtSc Intermetallic Compounds

The ab-initio calculations were performed to investigate structural, electronic, thermal and elastic properties of the binary ductile intermetallic compounds PdSc and PtSc with B2 (CsCl-type) structure using full potential linear augmented plane wave method (FP-LAPW) on the basis of density functional theory (DFT).The generalized gradient approximation (PBE-GGA and WC-GGA) is applied for PdSc and PtSc. The calculated equilibrium properties such as lattice constant (a0), bulk modulus (B) and its first derivative (B') are in better agreement with experimental and theoretical results. The elastic constants (C11, C12 and C44) of these compounds are reported first time. The value of B/GH ratio for both the compounds are larger than 1.75, indicating the ductile manner of these materials. From density of states and Band structure, it is observed that these intermetallic compounds are metallic in nature. We report first time mechanical and thermal properties which are predicted from the calculated values of elastic constants. Keywords: Intermetallic compounds, Ab-initio calculations, Thermal properties, Mechanical properties, Density of states, Ductilit

First Principles Study of Electronic, Elastic and Thermal Properties of B2-type RECd (RE =La, Ce and Pr) Compounds

The electronic, elastic and thermal properties of RECd (RE =La, Ce and Pr) intermetallic compounds crystallizing in B2-type structure have been studied using first principles density functional theory within generalized gradient approximation (GGA), and the local spin density approximation (LSDA) for the exchange correlation potential. From energy band structure and density of states we found that these intermetallics are metallic in nature. The thermal and mechanical properties are predicted from the calculated values of elastic constants. The ductility of these compounds is determined by calculating the bulk to shear ratio B/GH. Our calculated results indicate that PrCd is most ductile amongst all the RECd compounds. To the best of our knowledge this is the first theoretical prediction of the elastic properties of these compounds. Keywords: Intermetallics, Density Functional Theory, Elastic Constant, Ductility

First Principles Study of Structural, Electronic, Elastic and Mechanical Properties of GdSn3 and YbSn3 Intermetallic Compounds

First principles study of structural, electronic, elastic and mechanical properties of ferromagnetic GdSn3 and non-magnetic YbSn3 rare-earth intermetallics, which crystallize in AuCu3-type structure, is performed using density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. The ground state calculations are carried out within PBE-GGA, PBE-sol GGA and LSDA approximations   for the exchange correlation potential. The calculated ground state properties such as lattice constants and bulk moduli agree well with the experiment as well as other theoretical results. We report elastic constants for these compounds for the first time. Both these compounds are found to be ductile in nature. The computed electronic band structures show metallic character. We also report mechanical properties of these compounds for the first time.    Keywords: Rare-earth; Density functional theory; Elastic constants

High pressure structural phase transition of three diluted magnetic semiconducting compounds

410-413The high-pressure structural properties of three diluted magnetic semiconductor (DMS) compounds, viz Zn₁₋xMxSe (M=Cd, Fe and Mn) have been studied theoretically. The value of M-mole fraction x is given 0.16% for Fe, 0.1% for Cd and 0.24% for Mn. In order to investigate the high-pressure properties of these compounds, the two body potential approach has been used, which includes Coulomb term, short range repulsion and van der Waal interactions. It has been established that the potential used predict correctly the stability of zinc blende structure (ZBS) at ambient pressure. A good agreement between the experiment and the theoretical results has been achieved. The lattice parameter of all DMS ternary alloys obeys Vegards law very closely showing the linear dependence of lattice parameter on impurity composition. The 11.8, 9.3 and 9.2 GPa as phase transition pressure and 17%, 18.8% and 19% as percentage volume collapse for ZnFeSe, ZnMnSe and ZnCdSe alloys respectively, have been reported. This shows that these compounds get largely compressed during phase transition, though the % volume collapse overestimates the measured values. It has also been observed that the values of phase transition pressure for these alloys are less than their parent compound ZnSe (Pt= 14.4 GPa

High-pressure behaviour of rare earth mono bismuthides

459-464Pressure induced structural phase transition of mono-bismuthides of cerium, praseodymium, uranium and plutonium (REBi, RE= Ce, Pr, U and Pu) has been studied theoretically by using suitable two body inter-ionic potential which parametrically includes the effect of Coulomb screening by the delocalized f electrons of rare earth (RE) ion. The anomalous structural properties of these bismuthides, where Bi ion has the largest ionic radius, have been studied to investigate the role of f electrons on the structural phase transition. Except UBi, all the three compounds transform to body -centered tetragonal (BCT) structure at high pressure. UBi prefers to transform to cubic CsCl phase at high pressure. A static simulation technique has been used to calculate the equation of state, change in anion-anion and anion-cation distances with increasing pressure, for these compounds. The important finding is that, from the total energy point of view except UBi, all the compounds prefer to transform to BCT structure than CsCl structure at high pressure

Ab initio calculations of B

Spin polarized ab initio calculations have been carried out to study the structural, electronic, elastic and thermal properties of RHg (R = Ce, Pr, Eu and Gd) intermetallic compounds in B2 structure. The calculations have been performed by using both generalized gradient approximation (GGA) and local spin density approximation (LSDA). The calculated value of lattice constant (a0) for these compounds with GGA is in better agreement with the experimental data than those with LSDA. Bulk modulus (B), first-order pressure derivative of bulk modulus and magnetic moment (μB) are also presented. The energy band structure and electron density of states show the occupancy of 4f states for light as well as heavy rare earth atom. The elastic constants are predicted from which all the related mechanical properties like Poisson’s ratio (σ), Young’s modulus (E), shear modulus (GH) and anisotropy factor (A) are calculated. The ductility or brittleness of these compounds is predicted from Pugh’s rule (B/GH) and Cauchy pressure (C12 − C44). The Debye temperature (θD) is estimated from the average sound velocity, which have not been calculated and measured yet