Synthetic strategies for new inorganic oxide fluorides and oxide sulfates

The low temperature fluorination of low dimensional mixed metal oxides can be achieved in a variety of ways to provide new structures and modified ele ctronic characteristics. The potential of these methods for the synthesis o f new materials is considered, with particular reference to the fields of c opper oxide superconductors and layered manganese oxide colossal magnetores istance (CMR) phases; in both areas, careful structural and electronic cont rol is necessary for optimised properties. The fluorination mechanisms are quite complex, and this paper describes the synthesis of three new oxide fl uorides: La1.9Sr1.1Cu2O5F2, PbSr2YCu3O6F4 and La1.2Sr1.8Mn2O7F2, via proces ses which involve anion insertion, anion substitution and cation extraction . The use of a related strategy to incorporate more complex anions into oxi des is also discussed, and the assimilation of SO42- ions into Bi2O3 to giv e phases of composition Bi2O3-x(SO4)(x) is described.