Navegando por Autor "Maia, I."
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Artigo Ceramic pigment obtained by polymeric precursors(Elsevier, 2005-04) Cunha, Jardel Dantas da; Melo, Dulce Maria de Araújo; Martinelli, Antonio Eduardo; Melo, Marcus Antônio de Freitas; Maia, I.; Cunha, S.D.Fe2O3 has been used as ceramic pigment due to excellent colorimetric characteristics combined with thermal stability. The introduction of La+3 to Fe2O3 yields the precipitation of the perovskyte structure (LaFeO3) with corresponding differences in the color of the resulting pigment. The compound was synthesized from polymeric precursors and characterized by thermal and colorimetric analyses, infrared and UV–visible spectroscopy, and X ray diffraction. The characteristic light brown color of Fe2O3 changed to orange with the addition of La+3. As the calcination temperature increased from 900 °C to 1100 °C the pigment darkened as a result of the reduction of Fe+3 → Fe+2 with corresponding change of the colorimetric coordinates from L* a* b* = 49.003, 10.541, 12.609 to L* a* b* = 31.279, 6.096, 6.877