Synthesis of a Zircon-Cadmium Sulfo Selenide Pigment by a Sol-Gel Technique

Preparation of fire red cadmium sulfo- selenide pigments based on zircon via solid-state reactions encountered with some difficulties. Undesirable reactivity and inadequate homogeneity of components are two important problems, which counteracted on completely covering of color agents by zirconium silicate and so stable production of these materials. It has shown that by using a sol-gel method the above-mentioned problem will be eliminated and a desirable color shade can be obtained. In the sol-gel process, at first a precipitatant was prepared by mixing of Se (dissolved in sodium sulfide solution) and a cadmium sulfate-zirconium acetate solution. Gelation was occurred by adding a diluted sodium silicate solution into the washed and dried precipitant. The mineralizer was lithium fluoride, which was added to the washed/dried gel. Calcinations of the later compound were done at about 950 deg C. The experiments showed that the relative volume of zircon to cadmium sulfo selenide has an important role on a complete encapsulation of colorants and so on quality of pigment. According to our experiment, the optimum relative volume of colorant agent to zircon was determined as bout 40/60.