Influence of crystallinity on chromatic parameters of ceramic pigments preparation by Sol-Gel method and solid state method

Sol-gel processing is under intense world-wide investigation, particularly for synthesis of advanced ceramics. Advantages of sol-gel processing over classical solid-state reactions improve chemical properties due to mixing at the colloidal level, lower reaction temperatures and hence decrease production costs. Willemite ceramic pigments (Zn,Co)2SiO4 have been prepared in two ways: by means of a sol-gel method and by a solid-state method. Solid-state ceramic pigments are prepared by solid-state reaction between powders. The starting substance in the sol-gel method was a tetraethylorthosilicate solution, Co(NO3)26H2O, Zn(NO3) 26H2O whereas like solid state reaction has been realized using Co3O4, ZnO, SiO2. The major aim of the study was to compare the two methods of pigment preparation in terms of temperature, homogeneity, colour intensity, crystallinity and environmental factors. The samples were heat treated up to 800°C -1000°C -1200°C (4 hours) and analyzed by X-ray diffraction, infrared spectroscopy, and EDX and SEM; chromatic spectroscopy data indicate a nearly tendency of colour intensity and a crystallinity increase with increasing peak intensity by sol-gel method