Synthesis of Monazite in Aqueous Solution

Abstract

Materials Research Laboratory, Nagoya Institute of Technology; Gokiso-cho, Showa-ku, Nagoya-shi 466 Japan Monazite (monoclinic cerium phosphate) was synthesized by precipitating it from the mixed solution of cerium (III) chloride and orthophosphoric acid at 50°C and in the pH range O.2-0.6. After aging for 28 days, monazite crystals showed platy habit at pH's O.2 and O.4, and prismatic habit at pH 0.6. Hexagonal cerium phosphate coexised with monazite at pH 0.6, but disappeared as the aging progressed.
The chemical formula of the synthesized monazite is given as CePO₄. The density is 5.16 g/cms. The unit cell parameters obtained from X-ray diffraction of powder are as follows; a= 6.787 A, b=7.O^2-9 A, c = 6.468 A, 8 =1O^2-°18'.