Ceramics-Silikáty 58 (2) 145-150 (2014)

STRUCTURE AND PROPERTIES OF Co_xZn_1-xAl₂O₄ NANOPIGMENTS FABRICATED BY GEL COMBUSTION METHOD

Cobalt aluminate (CoAl₂O₄) is a double oxide with a normal spinel structure which has been widely used in ceramic industry, but because of cobalt cost and its environmental problems, many researches were conducted to reduce cobalt in this spinel. Using Co_xZn_1-xAl₂O₄ instead of CoAl₂O₄ reduce production costs minimize the environmental damages, but its optical and physical properties have been changed by reduction of Co content. In this research, Co_xZn_1-xAl₂O₄ (x = 0; 0.25; 0.5; 0.75 and 1) ceramic pigments were synthesized by gel combustion method via glycine as a fuel and their reaction parameters, phase Structure, morphology and color were studied by XRD, TG/DTA, FTIR, CIELAB Colorimetric and FESEM respectively. Thermal analysis results showed an exothermic peak with about 80 % weight loss which was related to spinel formation at about 200°C. XRD results revealed that structure of pigments were spinel and they have average crystallite size below 64 nanometer in (311), (220) and (440) directions. The colorimetric results showed that color of pigments were changed from dark blue to light blue and this behavior was related to the Co/Zn ratio also their lightness and chroma were increased by increasing calcination temperature.

Keywords: Pigments, Spinel structure, Gel combustion, CIELAB colorimetric