Impact of the sintering temperature on the structural, optical and electrical properties of zinc aluminate

Abstract

In this manuscript, we have reported on the impact of the sintering temperature on the physical properties of the normal spinel cubic system of zinc aluminate (gahnite). The samples were synthesized by the co-precipitation technique and sintered at three different temperatures. The thermal and structural analysis was confirmed by the crystallization process of initial spinel phase (as-prepared sample) and crystalline phase (sintered sample) which was studied by using TG–DTA and X-ray diffraction techniques. The optical band gap is found to be a redshift as inferred from UV absorbance spectra and show insight on the structural development of the spinel aluminate structure. The tetrahedral and octahedral site occupations of Al3+ ion co-ordinates were analyzed through stretching and bending modes of vibration through FT-IR spectral analysis. The ultra-fine powder of zinc aluminate samples particle size was carried out by using transmission electron microscopy measurement and the chemical composition of elements present was examined by energy-dispersive X-ray spectroscopy analysis. The frequency dependence of dielectric constant and tan δ was measured at room temperature using Impedance analyzer. The Cole–Cole plot of the real and imaginary part of the dielectric constant reveals the grain and the grain boundary nature of the sintered samples. The real and imaginary parts of dielectric modulus were exposing the relaxation behavior of samples and the frequency-dependent AC conductivity analysis for sintered samples. The semiconducting nature of spinel zinc aluminate and the sintering effect of sample results in better enhancement of optical behavior with a low magnitude of dielectric loss properties, which is applicable for optoelectronic applications.