Reaction Condition for the Synthesis of Ultrafine Particles of the High‐Vacancy‐Content Zn(II)‐ Bearing Ferrites from Iron(III) Tartrate Solution

Abstract

Reaction conditions for the synthesis of ultraflne particles of ferrite solid Solutions between ZnFe2O4 and γ‐Fe2O3 rep‐resented by x(ZnFe2O4)‐ y(Fe3O4)‐ z(γ‐Fe2O3), where x + y + z = 1 (0.09 x 0.73, y 0.08,0.22 z 0.88) (high‐vacancy‐content Zn(II)‐ bearing ferrites), were studied using the strongly alkaline Solutions of Fe(III) tartrate con‐taining Zn(II) ions at 100°C. The crystal growth of the ferrite particles was enhanced with the Zn(II) ions in the reaction solution. The number of nuclei of the ferrite was dependent on the Fe(III) or the tartrate concentration, which influenced the ultraflne particle size of the ferrite. The average particle size of the high‐vacancy‐content Zn(II)‐ bearing ferrites ranged from 7 to 38 nm. The room‐temperature Mössbauer effect of the high‐vacancy‐content Zn(II)‐ bearing ferrite (x = 0.34–0.37, y 0.02, z = 0.62–0.65) revealed the superparamagnetic nature for ultrafine particle sizes less than 20 nm. The ferrite was transferred from superparamagnetic to ferrimagnetic with an increase in the particle size (>20 nm) at room temperature.