Impact of annealing on optimization of various thermal, structural, and optical parameters of spinel ‘gahnite’ for device fabrication

Abstract

Abstract The spinel ZnAl2O4 nanopowder has been prepared using the well-known citrate sol-gel technique in which citric acid act as an agent for chelation. The XRD examined the sample crystallinity and phase purity of the samples after annealing at subsequent temperatures. Corresponding functional groups were identified by FTIR. The Surface texture of the samples was interpreted by FE-SEM and HR-TEM, while the constituent elements were evaluated by EDS spectroscopy. The UV-DR spectroscopy exhibits that the bandgap can significantly be tailored in annealed samples owing to the intrinsic impurity energy levels. PL has demonstrated the shift in emission spectra using the site-selective direct and indirect excitations. The prominent emission in the visible region is further emphasized by CIE chromaticity graphs and their specific color coordinates. The decay analysis reveals that the spinel ‘Gahnite’ samples have higher decay constant when excited with direct bandgap energy. It is suggested that the ZnAl2O4 would be a promising substitute as a blue-emitting phosphor in modern photonics.