Effect of additive on synthesis of MnZn ferrite nanocrystal by hydrothermal crystallization

Abstract

The effect of additive RCOONa on the formation of MnZn ferrite homogeneous coprecipitation precursor was studied in this paper. The action of additive in the MnZn ferrite hydrothermal crystallization process was investigated according to crystal field theory and crystal growth unit theory. And the growth unit formation process was presented and its structure was illustrated. The results show that the precursor of MnZn ferrite is a colloidal mixture composed of Zn(OH)2, Fe(OH)2, Mn(OH)2, MnO(OH), MnO2·xH2O and so on, and dissolves in solution in the form of hydroxyl coordination tetrahedron and octahedron such as Zn(OH) 4 2− , Fe(OH) 4 2− , Fe(OH) 6 4− , Fe(OH) 4 − , Fe(OH) 5 3− , Mn(OH) 4 2− , Mn(OH) 6 3− etc., and the growth unit is formed by combination of the coordination polyhedra subsequently in the hydrothermal precess. The additive is beneficial to the formation of homogeneous precursor and has dispersive effect on the aggregation of the crystal growth unit by forming associate with hydrogen bond, which is beneficial to the synthesis of the pure product with a tiny size and a narrow size distribution.