1. Effect of the calcination temperature on the cation distribution and optical properties of Mg0.5Co0.5CrAlO4 spinel pigment
- Author
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Xiangchun Yin, Hao Feng, Jianguo Huang, Yiqun Wang, Xiaoyang Wang, Jinfeng Li, and Zidie Pu
- Subjects
Materials science ,Absorption spectroscopy ,Analytical chemistry ,02 engineering and technology ,engineering.material ,01 natural sciences ,law.invention ,X-ray photoelectron spectroscopy ,law ,Spectrophotometry ,0103 physical sciences ,Materials Chemistry ,medicine ,Calcination ,010302 applied physics ,medicine.diagnostic_test ,Rietveld refinement ,Process Chemistry and Technology ,Spinel ,021001 nanoscience & nanotechnology ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Octahedron ,Ceramics and Composites ,engineering ,Absorption (chemistry) ,0210 nano-technology - Abstract
In this study, a blue-green pigment has been prepared by partially replace Co2+ and Cr3+ in CoCr2O4 spinel structure with Mg2+ and Al3+ using a gel casting method The gel precursor was calcined at various temperatures (900–1400 °C) to obtain Mg0.5Co0.5CrAlO4 spinel pigment. Combining the Rietveld refinement method of XRD and peak fitting of XPS high-resolution spectra, the relationships between the cation distributions (Co2+, Mg2+, Al3+, and Cr3+) in the tetrahedron and octahedron of the spinel structure and the calcination temperature were examined. In the octahedron, the contents of Co2+ and Al3+ decreased with increasing calcination temperature, and the Mg2+ and Cr3+ contents exhibited the opposite trend. The bond lengths of A-O and B–O change with increasing calcination temperature, thereby leading to a change in the unit cell. The optical performance of the pigments was investigated via UV–vis and CIE L*a*b* spectrophotometry, and the study shows that the blue-green hue of the pigment powder is caused by the absorption at υ3~υ8 (370 nm–640 nm) in the visible light region. The varied contents of Co2+ and Cr3+ in the spinel structure among calcination temperatures cause the absorption spectrum intensity change, thereby resulting in various blue-green tones. This study lays the foundations for subsequent investigations of colour modification in MgxCo1-xAlyCr2-yO4 spinel.
- Published
- 2021