Fast Synthesis of Co3O4 by Microwave-Assisted Hydrothermal Treatment

Abstract

This work describes a fast and simple procedure that combines the virtues of the microwave-assisted hydrothermal method with an oxidizing agent to produce Co3O4 nanocubes and nanoplates. We observed that particle morphology and size depend on the synthesis time and oxidizing agent (urea and hydrogen peroxide). The X-ray diffraction results showed that the samples are single phase, with crystallite sizes of approximately 30 nm. A similar crystalline domain is observed in the transmission electronic images. Magnetic measurements revealed the influence of the size and morphology of the particles on the magnetic curves. These measurements on the nanoplate samples revealed a paramagnetic behaviour at higher temperatures, and the presence of a cusp at that temperature was defined as TP. The TP decreases from 36 K to 21 K when the size of the plate particles decreases from 70 nm to 10 nm. These samples also present weak ferromagnetism below TP, which is attributed to a superparamagnetic blockade state. The nanocube samples have a lower magnetic susceptibility magnitude and weak ferromagnetism behaviour at room temperature. Our results show that this synthesis produces Co3O4 nanoplates and nanocubes with interesting magnetic properties related to their shape and size.