Synthesis of novel red phosphate pigments from manganese carbonate to imitate natrophilite

Síntese de novos pigmentos de fosfato vermelho de carbonato de manganês como imitação da natrofilita

Abstract

A novel red pigment, sodium manganese phosphate (NaMnPO₄), imitating natrophilite, was synthesized from manganese carbonate by heating under various conditions. The powders obtained were investigated by X-ray diffraction (XRD) analysis, infrared spectroscopy, ultraviolet-visible reflectance spectroscopy, and L*a*b* color space. Samples synthesized at 500-800 °C presented XRD patterns associated with NaMnPO₄. By heating at a higher temperature, the samples exhibited lighter color. The sample synthesized at 700 °C indicated the highest a* value. Furthermore, the effects of varying relative amounts of constituents were also studied. The temperature and period of heating, volume of water, and phosphate content affected the color phase of the pigments.

Keywords:
red pigment; natural ores; phosphate materials