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Item Metadata only Structural investigation and optical properties of cobalt aluminate pigments derived from thermal decomposition of mixed-metal nitrate co-crystals(2022-07-01) Yaemphutchong S.; Wattanathana W.; Chansaenpak K.; Singkammo S.; Kanjanaboos P.; Siri-apai P.; Janejobsakonkit S.; Pipattanaporn P.; Suetrong N.; Wannapaiboon S.; Hanlumyuang Y.; Mahidol UniversityIn this study, the coloration mechanism of cobalt aluminate spinel materials derived by thermal decomposition of the co-crystallized mixed-metal precursors has been reported. The structural alteration of cobalt aluminates, along with the origins... properties suggested that the coloration can be modified by controlling Co2+/Co3+ contents and their site occupancies in the spinel structure by adjusting calcination temperatures and selecting the counter ions with appropriate oxidizing power. The interplaysItem Metadata only Effect of triethanolamine chelating agent on crystallinities, phase purities, and optical properties of zinc aluminate spinel synthesized by thermal decomposition(2022-03-15) Pipattanaporn P.; Pansiri P.; Kumpeerakij P.; Yaemphutchong S.; Siri-apai P.; Suetrong N.; Chansaenpak K.; Singkammo S.; Kanjanaboos P.; Hanlumyuang Y.; Wannapaiboon S.; Wattanathana W.; Mahidol UniversityZinc 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.