Theoretical Investigations of Structural Phase Transitions and Magnetic, Electronic and Thermal Properties of DyNi: Under High Pressures and Temperatures

Present work is influenced by the requirement of investigation of rare earth intermetallics due to the nonavailability of theoretical details and least information from experimental results. An attempt has been made to analyse the structural, electronic, magnetic and thermal properties of DyNi using full potential linear augmented plane wave method based on density functional theory. DyNi differs from other members of lanthanides nickelates as in ground state it crystallizes in FeB phase rather than orthorhombic CrB structure. The equilibrium lattice constant, bulk modulus, and pressure derivative of bulk modulus are presented in four polymorphs (FeB, CrB, CsCl and NaCl) of DyNi. At equilibrium the cell volume of DyNi for FeB structure has been calculated as 1098.16？Bohr3 which is comparable well with the experimental value 1074.75？Bohr3. The electronic band structure has been presented for FeB phase. The results for thermal properties, namely, thermal expansion coefficient, Gruneisen parameter, specific heat and Debye temperature at higher pressure and temperatures have been reported. The magnetic moments at equilibrium lattice constants have also been tabulated as the rare earth ions associated with large magnetic moments increase their utility in industrial field for the fabrication of electronic devices due to their magnetocaloric effect used in magnetic refrigeration. 1. Introduction Because of the technological importance, the rare earth compounds have attracted interest of the experimental as well as the theoretical scientists during past decade. The rare earth elements on combining with transition metals show peculiar characteristics like good oxidation resistance and excellent strength [1]. Due to large magnetic moments and magnetocaloric effect (MCE) they also have applications in the fabrication of permanent magnets, magnetostrictive devices, magnetooptical recorders [2] and magnetic refrigeration [3–10]. These are also taken as first choice for the purpose of hydrogen storage materials [11]. Among all transition metals nickel is one of the promising materials in its pure form and also in alloy form doped with other materials. The structural parameters of some Gadolinium and Dysprosium intermetallics and their related compounds have been reported by Baenziger and Moriarty Jr. [12]. A sample of polycrystalline DyNi was prepared by Tripathy et al. [13] and its magnetocaloric effects have been studied on varying temperature scale by using powder X-ray diffractogram. Later, the magnetic properties of lanthanides-nickel intermetallic compounds and