Effect of triethanolamine chelating agent on crystallinities, phase purities, and optical properties of zinc aluminate spinel synthesized by thermal decomposition

Zinc aluminates form a niche class of ceramics, which are useful in various applications, including photoelectronic devices, catalysts, and high efficacy optical materials. Selecting appropriate starting precursors is the key impertive to control synthetic parameters in ceramics syntheses for the improvement of phase purity and corresponding physicochemical properties. The current study reports the successful preparation of high crystallinity and purity of ZnAl₂O₄ via thermal decomposition of the metal complex precursor using triethanolamine (TEA) as the additive and chelating agent. The effects of calcination temperatures and the existence of TEA on the formation of the desired ZnAl₂O₄ and the suppression of ZnO impurity are thoroughly investigated. Herein, the correlation between the in-depth analysis of the thermal decomposition profile of the mixed metal-TEA precursor and the characteristic features of the obtained ZnAl₂O₄ product are highlighted. The variation of optical bandgap energy of the derived materials by controlling the structural defects via a variation of synthetic parameters is explored. The obtained results show strong evidence that the ZnAl₂O₄ powders derived from the thermal decomposition of the mixed metal-TEA precursor are superior in terms of crystallinity, phase purity, and optical properties to those without using the TEA chelating agent.