Supercritical hydrothermal synthesis of highly crystalline lanthanum zirconate nanoparticles

Pyrochlore La2Zr2O7 nanoparticles were synthesised in supercritical water at 450 degrees C under a relatively short reaction time. Compared to traditional methods, e.g. solid-state reactions, hydrothermal methods, highly crystalline pyrochlore La2Zr2O7 nanoparticles were obtained even under such mild conditions. Furthermore, the supercritical hydrothermal synthesis of La2Zr2O7 nanoparticles was highly sensitive to the solution pH employed, as La(OH)(3) and ZrO2 were formed instead of La2Zr2O7 at pH 10 or lower, pH-controlled dissolution of La (OH)(3) and ZrO2 thus regulated the formation and growth of La2Zr2O7. This environmentally benign supercritical hydrothermal process will serve as a novel synthetic method for the preparation of La(2)Zr(2)O(7 )with replacing conventional processes.