The calculated defect properties of La2CuO4related to high-Tcsuperconductivity

Abstract

Calculations are reported of perfect lattice and defect properties of the orthorhombic and tetragonal phases of La₂CuO₄ related to high-T _c superconductivity. The theoretical methods are broadly similar to those used previously for a wide variety of ceramic oxides. Included in the perfect lattice properties are the structure, dielectric and elastic constants, the phase-transition temperature and the phonon densities of states. The defect properties discussed are the fundamental lattice and electronic disorder, non-stoichiometry, doping by + 1, + 2 and + 3 charged impurities, including Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺, and defect association.