OPTIMIZATION OF HYDROTHERMAL SYNTHESIS OF PLATE-LIKE HYDRATED CERIUM PHOSPHATES AND THEIR PHOTOCHEMICAL PROPERTIES

Abstract

Plate-like hydrated cerium phosphate, Ce 2 (PO 4) 2 HPO 4 ・H 2 O, has attracted attention because of its unique UV-shielding ability with excellent comfort when applied on the skin. Optimization of preparation conditions of hydrated cerium phosphate is required to obtain medium size plate-like particles of 5-50 µm in diameter which provide good comfort for human skin. Plate-like hydrated cerium phosphate, ca 20 µm in diameter, was obtained by the hydrothermal reaction of Ce(SO 4) 2 in H 3 PO 4 aqueous solution at 200 o C for 3 h. The sample showed excellent comfort, absorption ability of light less than 450 nm of wavelength and lower oxidation catalytic activity than undoped ceria.