OXYGEN INTERSTITIAL DEFECTS IN HIGH-T-C OXIDES

Atomistic lattice calculations are reported of the energetics associat ed with the formation of oxygen interstitial defects in La2CuO4, Nd2Cu O4, LaNdCuO4, and YBa2Cu3O6. The location and charge state of the addi tional oxygen are considered and hole-interstitial association energie s estimated. The last of these varies considerably from system to syst em. The implications for the high-T-c behaviour of these materials, in cluding the effects of fluorination on La2CuO4, and Nd2CuO4, are discu ssed in detail.