Oxygen-defect perovskites

Tarascon JM, Greene LH, McKirmon WR, Htrll GW, Geballe TH (1987) Superconductivity at 40 K in the oxygen-defect perovskites La2 cSr Cu04 y. Science 235 1373-1376 Taylor M, Brown GE (1976) High-temperatrrre structrrral study of the P2 /a-A2/a phase transition in synthetic titanite, CaTiSiOs. Am Mineral 61 435-447... 

The discovery by Wu et al. (1) of superconductivity at 9SK in a mixed-phase sample in the Y-Ba-Cu-0 system has stimulated an unprecedented amount of research effort directed at solving the structures of the phase(s) responsible for superconductivity. In this paper we will present the results of the first single-crystal structure analyses of the phases present in these samples to be carried out (2), and then review the additional structural information now available in relation to the previously determined structures of other oxygen defect perovskites. 

The superconducting behavior in oxygen defect perovskite oxides is found to depend on the amount and order of oxygen in the structure. In the case of YjBa C y, the highest and sharpest transitions are related to ordering of one-dimensional Cu-O ribbons in the structure which are in turn coupled to a network of adjacent 2-dimensional Cu-O sheets. The isostructural rare earth derivatives of YjBa-jC C y are found to display similar behavior. 

C.T. Prewitt Oxygen-defect perovskites and the 93-K superconductor, American Chemical Society Symposium Series 351, Chemistry of high-temperature superconductors, New Orleans 1987, 2.38... 

Ueda, Y. and Nakayama, N. (1998) Electron diffraction study of oxygen-defect perovskite CaVOs-. Solid State Ionics, 108, 303-306. 

Poeppekneier, K.R., Leonowitz, M.E., and Longo, J.M. CaMn02.5 and Ca2Mn03 5 — New oxygen-defect perovskite-type oxides. J. Solid State Chem. 1982, 44, 89-98. 

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