About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
Journal of Solid State Chemistry
Paper
Solid state chemistry of new perovskite and ruddlesden-popper phases in the la2o3-cao-cuo system at high pressures
Abstract
The crystal chemistry of the system LaO1.5-CaO-CuO at the 1:1:2 composition was studied at high pressures with the goal of stabilizing new perovskite cuprates with two-dimensional ordering of La, Ca cations and oxygen vacancies. Several phases, including the perovskites La4Ca4Cu8O20, La4Ca4Cu88O18 and the Ruddlesden-Popper (RP) phase La2Ca2Cu3O8, containing three copper oxide layers (n = 3), were revealed for the first time. The results are very sensitive to experimental conditions, and a variety of reaction channels are observed at the 1:1:2 composition depending on the choice of total pressure, Po2, temperature, and annealing conditions. The perovskite-related phases at this composition exhibited A-site cation disorder and three-dimensional ordering of oxygen vacancies. The Ruddlesden-Popper phase required the substitution of Sr on the A-sites to be metastably retained at room temperature. Due to its thermal instability, the RP phase could not be doped to a carrier concentration at which superconductivity might be observed. © 1994 Academic Press, Inc.