Synthesis and characterization of Ca3Co4O9 micro-nanopowders by sol–gel-molten salt method

Abstract

Ca3Co4O9 micro-nanopowder was synthesized by Sol–gel-molten-salt method. The effects of molten salt system, secondary calcination temperature, and holding time on the synthesis of Ca3Co4O9 have been systematically investigated. The results show that the optimal solution for the synthesis of final Ca3Co4O9 powder by the Sol–gel-molten-salt is as follows: The calcium cobaltate precursor powders were obtained by holding the xerogel at 850 °C for 2 h at a heating rate of 3 °C/min and then adding the single-phase molten salt with a ratio of precursor: K2CO3\u2009=\u20091:7 at a temperature of 850 °C for 5 h to obtain calcium cobaltate powder. The thickness of the product is about 0.2 μm, the maximum crystal diameter can reach about 10 μm, and the grain distribution is relatively uniform under the best process conditions. Compared with a single sol–gel method, high-purity Ca3Co4O9 powder can be synthesized by the sol–gel method combined with molten salt method.