Optical and Dielectric Properties of Magnesium Aluminate Spinel with Varying Degrees of Stoichiometry

This study investigated magnesium aluminate spinel's optical and dielectric properties with varying stoichiometry degrees. The nanoparticles were prepared using a wet chemical route technique, and different molar ratios of Mg/Al (1:2, 1:1, 2:1) were used to create both stoichiometric and non-stoichiometric samples. The resulting nano-powders were sintered at 1100°C, and their morphological properties were investigated using X-ray diffraction (XRD), which showed that all samples had a cubic structure. However, the crystallinity and crystallite size decreased as the Mg/Al ratio moved from 1:2 to 1:1 and then to 2:1. UV-Vis spectroscopy was used to determine the optical bandgap energy, and fluorescence spectra showed multicolored emission since the presence of various defect states in the energy gap, such as anionic, cationic, antisite, Schottky, and interstitial. The dielectric properties were studied in the 500 Hz to 1 MHz frequency range, and the calculated alternating current (AC) conductivity increased with frequency. These findings suggest that the prepared materials may be suitable for optoelectronic devices, microwave applications, and semiconductor devices.