Synthesis of gold pearlescent pigment via heat treatment of mica

Pearlescent pigments are widely used to decorate ceramic tableware and architectural ceramics. Coating of mica with high-refractive metal oxides such as titanium oxide is one of the most important synthesis methods of these pigments. However, this process is expensive and long. Moreover, because of the complexity of the process, it is difficult to control and obtain consistent color. This depends on the thickness of the deposited thin film layer. In this study, a low-cost and easy method is proposed to synthesize gold pearlescent pigment. In this case, bulk mica (phlogopite) is heat-treated at appropriate temperatures, determined from related differential thermal analysis (DTA) profiles. Then, the obtained materials are milled for about 2 h and sieved in the 20–60 μm range. X-ray diffraction (XRD) and goniospectrophotometery are used for characterization of the obtained pigment. XRD results showed a few changes in related patterns of the primary sample. In this case, a part of the initial phase of phlogopite was changed to Mg 2 SiO 4 (forsterite) and K 2 MgSi 5 O 12 (leucite). Goniospectrophotometer results demonstrated the highest reflectance in the 560–570 nm range (yellow color), and showed a satisfactory level of brightness and lightness of the obtained gold color.