Synthesis and characterization of Ti(IV)-substituted calcium hydroxyapatite particles by forced hydrolysis of Ca(OH) sub(2)-Na sub(5)P sub(3)O sub(10)-TiCl sub(4) mixed solution

Ti(IV)-substituted calcium hydroxyapatite (TiHap) particles were prepared by aging Ca(OH) sub(2), TiCl sub(4), and sodium triphosphate (sodium tripolyphosphate, Natpp: Na sub(5)P sub(3)O sub(10)) mixed solution at 100 degree C for 18 h. The ellipsoidal secondary TiHap particles with ca. 100 similar to 150 nm in length composing by aggregation of small ellipsoidal primary particles with ca. 20 nm in length were produced at atomic ratio of Ti/(Ca+Ti) [X sub(Ti)][lE]0.2. The in situ IR spectra of these TiHap particles exhibited very small bulk OH super(-) band at 3,570 cm super(-1). This result indicated that the TiHap particles were formed by aggregation of fine primary particles and OH super(-) ions along with c-axis in the primary particles were disordered. The TiHap particles with Ca/P atomic ratio larger than theoretical value of 1.67 did not exhibit surface P-OH groups at 3,659 and 3,682 cm super(-1). The diffuse reflectance UV spectra of TiHap particles revealed that these particles have a UV absorption property, especially fabricated at X sub(Ti) = 0.1. The particles prepared at X sub(Ti) = 0.6 and 0.8 were amorphous and nanoparticles with 5 similar to 10 nm in diameter, but those precipitated at X sub(Ti) = 1.0 were poorly crystallized anataze-type TiO sub(2) nanoparticles.