Solid‐State Synthesis of LaCoO3 Perovskite Nanocrystals.

A solid-state reaction process has been developed to synthesize perovskite-type LaCoO 3 nanocrystals with grain diameters of 15-40 nm. In the first step of the preparation, ∼5 nm composite hydroxide nanoparticles are synthesized by the solid-state reaction of La(NO 3 ) 3 .nH 2 O and Co(NO 3 ) 2 .6H 2 O with KOH at ambient temperature. A perovskite-type rhombohedral LaCoO 3 phase appears at 550°C, after the hydroxide has been calcined at various temperatures. The phase transformation process is complete at ∼800°C, yielding a single-phase binary oxide. The results indicate that the new process is convenient, inexpensive, and effective for obtaining LaCoO 3 nanocrystals with high yield.