SYNTHESIS AND CHARACTERIZATION OF Ce(III)-SUBSTITUTED CALCIUM HYDROXYAPATITE PARTICLES BY FORCED HYDROLYSIS OF Ca(OH)<SUB>2</SUB>-Na<SUB>5</SUB>P<SUB>3</SUB>O<SUB>10</SUB>-CeCl<SUB>3</SUB>-MIXED SOLUTION

Abstract

The formation of large and morphologically uniform Ce(III)-doped calcium hydroxyapatite (CeHap) particles by a forced hydrolysis method using Ca(OH)2-Na5P3O10-CeCl3-mixed solutions was investigated and the precipitated particles were characterized by various methods. The ellipsoidal secondary particles with ca. 115 nm in particle length of those were composed by aggregation of ellipsoidal primary particles with ca. 20 nm in diameter were produced at XCe (Ce/(Ca+Ce) atomic ratio) = 0. The morphology of the particles was changed to rod-like with ca. 50~100 nm in width and 100~300 nm in length at 0.1≦XCe≦0.2. Furthermore, particle shape varied to needle-like at 0.4≦XCe≦0.8 and finally fine spherical particles with 5~10 nm in diameter were precipitated at XCe=1.0. The XRD patterns of the particles indicated that highly crystallized pure CeHap particles are produced at XCe≦0.2. On the contrary, the needle-like and very fine spherical particles precipitated at XCe=0.4~1.0 were identified as CePO4. The time resolved TEM and XRD measurements suggested that the rod-like large CeHap particles are produced by the Ostwald ripening mechanism. The diffuse reflectance UV measurement indicated that CeHap particles have a UV absorption property, especially produced at XCe=0.15.