Low-temperature chemical synthesis of lanthanum copper oxide

Lanthanum copper oxide (La2CuO4) precursors for superconductors were synthe sized by acetate/nitrate self-propagating combustion synthesis (SPCS) in th e presence of urea at different ratio of O/F. Phase-pure La2CuO4 powder cou ld be obtained by calcining the as-prepared precursors at temperature as lo w as 600 degreesC. It was demonstrated that the ratio of O/F strongly influ enced the composition and morphology of the precursors as well as the sampl es calcined at various temperatures. We have studied the synthesis conditio ns, demonstrating the existence of a relationship between the calcination t emperature and the calcination time needed to obtain the pure phase. An int eresting stereoscopic network structure was observed on the samples synthes ized at the ratio of O/F = 0.20, morphology evolution of the samples was al so investigated. The emission of H2O as well as CO2 was responsible for the formation of the structure during the calcination process. (C) 2001 Kluwer Academic Publishers.