Structural, electronic and elastic properties of RERu2 (RE = Pr, Nd and Sm) Laves phase compounds

Bonding nature, structural, electronic, magnetic and elastic properties of RERu2 (RE = Pr, Nd and Sm) Laves phase compounds have been studied using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory. The LSDA and LSDA+U approach has been used to get accurate results because of the presence of the highly localized 4f electron of RE (RE = Pr, Nd and Sm) atoms. The calculated lattice parameters and magnetic moments are in good agreement with available experimental results. The electronic and bonding properties have been resolved in terms of band structures, DOS, Fermi surfaces and charge density difference plots, which confirm their metallic character. From the charge density difference plots it has been observed that these compounds show mixed covalent-ionic bonding nature simultaneously and metallic bonding is also present. The mechanical properties and Debye temperature have been predicted from the calculated elastic constants. The ductility of these Laves phase compounds have been predicted in accordance with Pugh’s criteria

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

Pressure Induced Structural Phase Transition and Elastic Properties of Lutetium Chalcogenides (LuX, X: S, Se and Te)

We have investigated, the cohesive energies, pressure-volume relationship, phase transition pressure (Pt) and elastic constants for lutetium chalcogenides (LuX, X: S, Se, Te), using an interionic potential theory with modified ionic charge which includes Coulomb screening effect due to f-electrons.  These compounds undergo structural phase transition from NaCl (B1) to CsCl (B2) structure at high pressure (ranges from 10 to 60 GPa).  The B1 (NaCl) phase is found to be lower in energy than the B2 (CsCl) phase and more stable at zero pressure. Keywords: Rare earth chalcogenides; high pressure; elastic properties; equations-of-state;  phase transition

First Principles Study on Structural and Electronic Properties of REAg (RE= Y, La, Pr and Er) Intermetallics

We The structural, electronic and mechanical properties of binary B2 – type CsCl structured intermetallic compounds of Ag (ReAg, Re= Y, La, Pr and Er) have been studies systematically by means of first principles density functional theory within generalized gradient approximation. Ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B?) are obtained. The present results are in good agreement with the experimental and other theoretical calculation available. Amongst all the Intermetallics is found ErAg to be most ductile due to the presence of strong metallic bonding. Keywords: Intermetallic compounds; Density Functional Theory; Ductility; Electronic Structure

Structural Phase Transition and Electronic Properties of NdBi

The structural and electronic properties of NdBi from an electronic structure calculation have been presented.  The calculation is performed using self-consistent tight binding linear muffin tin orbital (TB-LMTO) method within the local density approximation (LDA).     The calculated equilibrium structural parameters are in good agreement with the available experimental results.  It is found that this compound shows metallic behavior under ambient condition and undergoes a structural phase transition from the NaCl structure to the CsCl structure at the pressure 20.1 GPa.  The electronic structures of NdBi under pressure are investigated.  It is found that NdBi have metalliation and the hybridizations of atoms in NdBi under pressure become stronger. Keywords: Phase transition, bulk modulus, band structure, density of states

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 on Structural, Electronic, Elastic and Thermal Properties of Equiatomic MTi (M = Fe, Co, Ni)

We have investigated the structural, electronic, elastic and thermal properties of MTi (M = Fe, Co and Ni) using ab-initio full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) and local spin density approximation (LSDA). We have calculated the ground state and electronic properties such as lattice constant (a0), bulk modulus (B), pressure derivative of bulk modulus (B') and density of states at Fermi level N(EF) which are in good agreement with experimental and available other theoretical results. The elastic constants (C11, C12 and C44) and mechanical properties such as Poisson’s ratio (? ), Young’s modulus (E), shear modulus (GH), anisotropic factor (A) are also calculated which are agree well with the experimental and other theoretical results. Ductility for these compounds have been analyzed by Pugh’s rule (B/GH ratio) and Cauchy pressure (C12 - C44). Our calculated results reveals that NiTi is most ductile amongst the MTi (M = Fe, Co and Ni) compounds.Keywords: Ab-initio, electronic properties, elastic properties, thermal properties

Structural and Electronic Properties of HfN: ab initio calculation

The structural and electronic properties of HfN from an electronic structure calculation have been presented.  The calculation is performed using self-consistent tight binding linear muffin tin orbital (TB-LMTO) method within the local density approximation (LDA).     The calculated equilibrium structural parameters are in good agreement with the available experimental results.  It is found that this compound shows metallic behavior under ambient condition.  The electronic structures of HfN in B1 phase are investigated.  It is found that HfN have strong metallization and the hybridizations of atoms in B1 phase. Keywords: Bulk modulus, band structure, density of states

Structural, Electronic and Elastic Properties of TMAl (TM=Co, Ni and Ru) Intermetallics: An ab-initio Study

The structural, electronic, elastic, mechanical and thermal properties of transition metal aluminides (CoAl, NiAl and RuAl) have been investigated systematically using first principle density functional theory (DFT). Ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B?) are calculated which show well agreement with the experimental and other theoretical results. The electronic properties have been analyzed quantitatively. The values of elastic constants are also reported. The ductility of these compounds has been analyzed using the Pugh’s rule, Cauchy’s pressure (C12-C44) and electronic structure.  Our calculated results indicate that NiAl is ductile while CoAl and RuAl are brittle. The elastic properties such as Young's modulus (E), Poisson's ratio (?) and anisotropic ratio (A) are also reported. We have also correlated the ductility and bonding behaviour of these compounds. Keywords: Density functional theory; intermetallic compounds; electronic properties; ductility; thermal properties