Microwave Assisted-Hydrothermal Synthesis of Nickel Ferrite Nanoparticles

Abstract

Nanomagnetic ferrite materials are of great technological importance in several industries due to their high performance, ease of preparation and low cost. The ferrite properties are based on composition, structure and methods of preparation. Nickel ferrite, NiFe2O4, was prepared by the simple microwave assisted-hydrothermal method. Nickel chloride and ferric chloride solutions (stoichiometric ratio of 1: 2 respectively) were mixed, the pH was raised to 10.5 and the mixture was heated at 180 °C in a closed Teflon vessel using a microwave oven at different periods of time (2 - 24 h). The formed powders were examined by XRD, TEM, and VSM. The intensity of nickel-ferrite in the XRD patterns increased with time owing to increase in crystallinity of the formed phase. The TEM images showed that, the size was in the range of 20-40 nm and contents of fine particles noticeably decreased with increasing reaction time to 4-6 hrs and contents of more regular cubic particles are formed. The NiFe2O4 magnetization was continuesly increased with raising the heating time from 2h (9 emu/g) to 24 h (43 emu/g) which may be due to the high purity and crystallinity of the formed NiFe2O4. The results showed that the properties of the formed ferrite can be tailored by controlling the heating time. Microwave assisted co-precipitation followed by hydrothermal digestion resulted in a substance of good homogeneity and crystallinity at a short time.