High-pressure synthesis and thermal decomposition of LaCuO3

The high-pressure synthesis of the rhombohedral LaCuO3 perovskite has been studied and optimized in terms of the applied pressure and temperature, the synthesis time and the amount of the oxidizer. Essentially single phase samples were obtained at temperatures above 1400 °C under an oxygen pressure of 5 GPa. The high oxygen pressures were generated using excess amounts of KClO4 as an external oxidizing agent. Upon heating under ambient pressure the stoichiometric high-pressure form of LaCuO3−y loses oxygen yielding various oxygen-deficient phases, and finally decomposes into La2CuO4 and CuO or Cu2O at approximately 800 °C.