Preparation and characterization of lanthanum nickel oxides by combined coprecipitation and molten salt reactions

This study deals with the preparation of the lanthanum nickel oxides by combined precipitation and molten salt reactions. The reagents such as LaCl3, NiCl2 and different alkali metal hydroxides were used to get the precursors in various compositions. They were reacted at 1073–1173 K to obtain the fine lanthanum nickel oxides (La2NiO4, LaNiO3) with a uniform particle size about 0.1 μm. LaNiO3 is unstable at high temperature and converted into La2NiO4. The powders coprecipitated with potassium hydroxide have good sinterability leading to less in electrical resistivity than those with sodium hydroxide or lithium hydroxide. These compounds with different compositions exhibit characteristics of Pauli paramagnetic materials. In correspondence with the change of phase ratios there are also changes in the mass susceptibility from 4.0×10−6 emu/(g-Gauss) for LaNiO3 to 1.25×10−6 emu/ (g-Gauss) for La2NiO4.