Synthesis and Characterizations of (Co _x Mg_{(2- x)})SiO₄ Forsterite Ceramic Pigments from Mirror Waste

Ceramic pigments have been widely used in a variety of industries because of their excellent properties, such as high thermal stability, low-cost productions, and simple manufacturing processes. Re-use of mirror waste, which consists of silicon dioxide greater than 70%, is a method that can reduce raw materials cost. In this work, ceramic pigment with forsterite structure, Mg₂SiO₄, was synthesized via conventional solid state reaction by using mirror waste as a precursor. Solid solutions of Co-doped forsterite pigment, Co_xMg_(2-x)SiO₄ where x = 0.02⁻1.6, were calcined at 1000 °C for 2 h. The calcined powders were characterized by X-ray diffraction technique (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectrophotometer, and color measurement (CIEL*a*b*). XRD results confirmed that forsterite phase was found as a main phase in the ceramic powder. However, the forsterite phase decreased with increased concentration of Co to x = 0.8⁻1.6. This could be because of the solubility limit of Co in solid solution. In addition, the use of mirror waste as a raw material was able to reduce calcination temperature compared to the use of oxide reagents. Color measurements or CIEL*a*b* color space of forsterite pigments were located in red-blue quadrant for Co-doped pigment.