Preparation, Characterization, and Thermal Stability of Lead Hydroxyapatite

✍ Scribed by Shigeru Sugiyama; Tomomi Nakanishi; Tomohiro Ishimura; Toshihiro Moriga; Hiromu Hayashi; Naoya Shigemoto; John B. Moffat

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 158 KB
• Volume: 143
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1998.8126

✦ Synopsis

Lead hydroxyapatites (PbHAp) have been prepared from H3PO4 and Pb(NO3)2 • 5PbO (1), the latter of which was obtained through dehydration of basic lead nitrates such as 2Pb(NO3)2 • 5Pb(OH)2 (2) and Pb(NO3)2 • 5Pb(OH)2 (3). The amount of 2 with respect to 3, as well as the quantity of an unidentified water-soluble compound (4), decreased with increasing reaction time. The dehydration of 2 and 3, but not of 4, yielded the desired compound with expected X-ray diffraction pattern and infrared spectra. When the prepared PbHAp was heated at 773, 973, and 1173 K for 3 h, the XRD patterns showed the apatite structure, respectively, but PbHAp heated at 1173 K was partly converted to an amorphous compound. At 1473 K, PbHAp completely melted. X-ray absorption fine structure analyses showed that the nearest-neighbor distance of the Pb-O bond in PbHAp was 2.18 A s , which was shorter than that of the Ca-O bond of calcium hydroxyapatite and Sr-O bond of strontium hydroxyapatite.