Synthesis of Mg1−xCoxAl2O4 blue pigments via combustion route

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Japan, 2011-05, Vol.22 (3), p.396-400
• Main Authors: Ianos, R, Lazau, R, Barvinschi, P
• Format: Article
• Language: English
• Subjects: Color measurement; Colour measurement; Combustion; Crystallites; Metal nitrates; Networks; Pigments; Specific surface; Synthesis
• ISSN: 0921-8831
• DOI: 10.1016/j.apt.2010.06.006

MgAl2O4 was used as a crystalline host network for the synthesis of cobalt-based blue ceramic pigments. Different compositions of Mg1-xCoxAl2O4 (x = 0.1-0.3) powders were prepared by the combustion reaction of corresponding metal nitrates with mixtures of urea and beta-alanine. The resultant powders were characterised using XRD, TGA/DTA, EDAX, SEM, BET method, DRS and CIEL*a*b* colour measurement. For x = 0.2, thermal analysis investigations showed that the combustion reaction occurred at 276 C. XRD confirmed the formation of the required solid solution and no additional thermal treatment was required. EDAX confirmed the purity of the as-prepared compound. The resulting powders had large surface areas, which varied from 8.7 to 62.6 m2/g. The crystallite size of the Mg1-xCoxAl2O4 powders was < 15 nm. Experimental results showed that as the proportion of Co2+ increased, the crystallite size decreased and the specific surface area increased. DRS of the Mg1-xCoxAl2O4 pigments confirmed the presence of tetrahedrally coordinated Co2+. CIEL*a*b* chromatic coordinates indicated that the bluest colour was obtained for x = 0.2.