The Cuprate Ln2CuO4 (Ln: Rare Earth): Synthesis, Crystallography, and Applications

Abstract

This chapter is concerned with a study of undoped and doped cuprates of the general formula Ln2CuO4 (Ln = rare-earth metal) and Ln2–xMxCuO4±δ (Ln = rare earth and M = Sr, Ba, Ca, Ln’, Bi, and 3d metal). The crystal structures of the undoped and doped cuprates having the notations (T, T′, T*, S, and O), significantly depend, however, on the synthetic route. The topotactic synthesis is a specific method, which allows the transformation of the cuprate from the T to T′ structure. The importance of these materials originates from the discovery of the unconventional superconductors of the Ce-doped Ln2CuO4. The cuprate materials could function as insulators or semiconductors which are valuable tools in optoelectronic applications. The doped cuprate materials are good ionic conductors and are found useful as electrodes in fuel cell applications. The undoped cuprates reveal high dielectric properties.