THE CALCULATED DEFECT PROPERTIES OF LA2CUO4 RELATED TO HIGH-TC SUPERCONDUCTIVITY

Calculations are reported of perfect lattice and defect properties of the orthorhombic and tetragonal phases of La//2CuO//4 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 plus 1, plus 2 and plus 3 charged impurities, including Mg**2** plus , Ca**2** plus , Sr**2** plus and Ba**2** plus , and defect association.