Vol. 2, Issue 1 (2018)
High pressure electronic phase transition, metallization and superconductivity in Rbl
Author(s): Y Ramola, C Nirmala Louis, A Amalraj
Abstract: The electronic phase transition, metallization and superconducting transition of the simple alkali iodide Rubidium Iodide (Rbl) is investigated through their band structure. The self-consistent band structure calculation is performed both in NaCl and CsCl structures using the full potential linear muffin-tin oRbltal (FP-LMTO) method. The equilibrium lattice constant, bulk modulus and the phase transition pressure at which the compound undergoes structural phase transition from NaCl to CsCl are predicted from the total energy calculations. The band structure, density of states (DOS), electronic charge distributions, metallization and superconducting transition temperature (Tc) of Rbl are obtained as a function of pressure for both in NaCl and CsCl structures. The density of states at the Fermi level (N(EF)) gets enhanced under pressure, which leads to metallization in Rbl. It is found that, the charge transfer from s and p states to d state causes structural phase transition and superconductivity in Rbl. The pressure corresponding to structural phase transition from NaCl structure (B1) to the CsCl structure (B2) is 0.021 Mbar in Rbl. This value is agreement with the experimental value of 0.02 Mbar. In Rbl, the metallization occurs through indirect closing of the band gap between G and H points at the reduced volume V/Vo=0.43 (CsCl structure), the corresponding metallization pressure is 1.228Mbar. Our results completely agree with the experimental observation of 1.31 Mbar. The highest Tc estimated is 2.151 K and the corresponding pressure is 4.945 Mbar in the NaCl structure and 0.107 K in the CsCl structure.