Combustion synthesis, structure, magnetic and optical properties of cobalt aluminate spinel nanocrystals

In-situ synthesis of spinel cobalt aluminate nanoparticles using aloe vera plant extract was carried out under microwave combustion (MCM) and conventional combustion (CCM) methods. On heating, the precursors yielded nano-sized CoAl2O4 spinel, which was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FT-IR), Scanning electron microscopy (SEM), UV-Visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The magnetic properties of the synthesized aluminates were investigated by room temperature vibrating sample magnetometry (VSM). The formation of a pure CoAl2O4 phase was confirmed by XRD and FT‐IR. Both the phase composition and the crystallite size of the spinel are controlled by the plant extract. The relatively low saturation magnetization (23.96 emu/g) of CoAl2O4-CCM shows that it is weak ferromagnetic in nature and high saturation magnetization (32.13 emu/g) of CoAl2O4-MCM confirms its ferromagnetic behavior.