Order-disorder in T, T', and T* phase: superconductors and related materials.
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.
González-Calbet
J M
JM
Departamento de Química Inorgánica, Facultad de Químicas, Universidad Complutense, Madrid, Spain.
Sayagués
M J
MJ
Varela
A
A
Alonso
J M
JM
Caneiro
A
A
Vallet-Regí
M
M
D004553:Electric Conductivity; D008854:Microscopy, Electron; D010087:Oxides / Q000737:chemistry*; D014961:X-Ray Diffraction
D010087:Oxides