Crystallization of nanosized Ni-Zn ferrite powders prepared by hydrothermal method

Nanosized powders of Ni0.5Zn0.5Fe2O4 with well-developed spinel phases were prepared by hydrothermal method. An average particle size of about 10-20 mn of Ni-Zn ferrite powder is obtained. Single-phase ferrites with a spinel structure began to form at a relatively low temperature (120degreesC) and a short holding time (1 h). The crystallization of the spinel ferrites was promoted by the increase in reaction temperature and time in the hydrothermal process. The crystallization kinetics between 100degreesC and 150degreesC with different durations was investigated by the X-ray diffraction data. It was observed that a random nucleation process dominates and gives a first-order equation. The activation energy for this process is calculated to be 56.2 kJ/mole. (C) 2003 Elsevier B.V. All rights reserved.