title: Order-disorder in T, T', and T* phase: superconductors and related materials.
abstract: After reviewing microstructural studies on superconducting materials showing T, T', and T* structural types, results are presented on the microstructure of some n-type superconductors and related materials prepared with accurate control of the oxygen stoichiometry. Electron microscopy is used to describe the ordering of interstitial oxygen defects in T-type La2NiO4 + delta leading to the formation of the n = 2 term of a homologous series with the general formula La8nNi4nO16n + 1. Structural transitions and superstructure formation in the Pr2-x-yCexSryCuO4-delta system are reported, where T, T', and T* phases are isolated as a function of both Ce and Sr content.
authors.affiliation: Departamento de Química Inorgánica, Facultad de Químicas, Universidad Complutense, Madrid, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: González-Calbet
authors.forename: M J
authors.initials: MJ
authors.lastname: Sayagués
authors.forename: A
authors.initials: A
authors.lastname: Varela
authors.forename: J M
authors.initials: JM
authors.lastname: Alonso
authors.forename: A
authors.initials: A
authors.lastname: Caneiro
authors.forename: M
authors.initials: M
authors.lastname: Vallet-Regí
mesh_terms: D004553:Electric Conductivity; D008854:Microscopy, Electron; D010087:Oxides / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D010087:Oxides