Ceramics-Silikáty 56, (4) 301 - 305 (2012)

Nano sized pigments with the general formula Co_xZn_1-xAl₂O₄ (x = 0, 0.2, 0.4, 0.6, 0.8, 1) were synthesized using chlorides by gel combustion method at 700, 800, 900, 1000, 1100^oC. DTA/TG, XRD, UV-Vis. and SEM were used to characterize the samples. The DTA results revealed that the formation of the spinel phase occurred at 600 to 670^oC. XRD results showed that all the samples, except those treated at 1000 and 1100^oC, were constituted of only one phase. The ones treated at 1000 and 1100^oC showed extra peaks related to Al₂O₃. The cobalt containing samples showed a low reflection in the range of 540 to 630 nm, corresponding to the absorption of the colors yellow and orange. Therefore, the cobalt containing samples demonstrated diverse blue colors. The results also revealed that by increasing the cobalt content, the crystallite size decreased from 32 to 9 nm, while by the rise in heat treatment temperature it decreased from 17 to 26. The SEM micrographs revealed the formation of nanosized pigments, with some degree of agglomeration.