Synthesis of novel phosphate pigments in imitation of Turquoise

Abstract

As novel blue pigment, various copper aluminum phosphate hydroxides imitated with Turquoise, CuAl₆(PO₄)₄(OH)₈•4H₂O, were synthesised by heating the mixture of copper oxide, aluminum hydroxide, and phosphoric acid. Furthermore, the similar chemical compositions with Turquoise were also studied. The obtained powders were estimated with X-ray diffraction (XRD), Infrared (IR) spectra, ultraviolet–visible (UV–Vis.) reflectance spectra, and L*a*b* color space. The heating temperature and time, volume of water were studied in this process. Further, the other related compositions were also investigated. The obtained materials had the XRD peaks of CuAl₆(PO₄)₄(OH)₈•4H₂O and CuO. The sample synthesised at 700 °C (3 h, 10 mL) indicated higher lightness than those prepared at other temperatures.

Keywords:

• Phosphate pigment
• Turquoise
• color