HYDROTHERMAL SYNTHESIS OF ULTRAFINE FERRITE PARTICLES

Abstract

Abstract Ultralfine Ni-, Co- and Zn-ferrite particles were synthesized by hydrothermal treatment of the same gel-like precipitates formed at room temperature. Round ultrafine particles were formed, whose size ranged from 6 to 16 nm, depending on hydrothermal conditions. The size distribution could be described by a log-normal function, and the geometric standard deviation defined as 84.1%-size/50%-side in the size distribution was determined to be about 1.2 regardless of hydrothermal temperature and time. The effect of the reaction conditions on the mean particle size was investigated. As the hydrothermal temperature rises, the particle size increases and crystallization is promoted. The effects of stirring speed in the autoclave and initial loadings of raw materials on the mean size of ferrites are negligibly small.