Phase transformation of calcium phenyl phosphate in calcium hydroxyapatite

Journal Article · Tue Jul 03 00:00:00 EDT 2007 · Materials Research Bulletin

DOI:https://doi.org/10.1016/j.materresbull.2006.10.003· OSTI ID:21000674

Tanaka, Hidekazu ^[1]; Ibaraki, Koshiro ^[1]; Uemura, Masao ^[1]; Hino, Ryozi ^[1]; Kandori, Kazuhiko ^[2]; Ishikawa, Tatsuo ^[2]

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1. Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan)
2. School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan)

Calcium phenyl phosphate (CaPP) was synthesized from a mixture of Ca(OH){sub 2} and phenyl phosphate (C{sub 6}H{sub 5}PO{sub 4}H{sub 2}) in an aqueous media. XRD pattern of CaPP exhibited five diffraction peaks at 2{theta} = 6.6, 13.3, 20.0, 26.8 and 33.7{sup o}. The d-spacing ratio of these peaks was ca. 1:1/2:1/3:1/4:1/5. The molar ratios of Ca/P and phenyl/P of CaPP were 1.0 and 0.92, respectively, and the chemical formula of the material was expressed as (C{sub 6}H{sub 5}PO{sub 4}){sub 0.92}(HPO{sub 4}){sub 0.08}Ca.1.3H{sub 2}O, similar to that of dicalcium phosphate dihydrate (CaHPO{sub 4}.2H{sub 2}O: DCPD). These results allowed us to infer that CaPP is composed of a multilayer alternating bilayer of phenyl groups of the phosphates and DCPD-like phase. The structure of the material was essentially not altered after aging at pH 9.0-11.0 and 85 deg. C in an aqueous media. While, after aging at pH {<=}8.0, the diffraction peaks of CaPP were suddenly weakened and disappeared at pH 7.0. Besides, new peaks due to calcium hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}: Hap) appeared and their intensity was strengthened with decreasing the solution pH. TEM observation revealed that the Hap particles formed at pH 6.0 are fibrous with ca. 1.5 {mu}m in length and ca. 0.2 {mu}m in width. From these results, it is presumed that the layered CaPP was dissolved, hydrolyzed and reprecipitated to fibrous Hap particles at pH {<=}8.0 and 85 deg. C in aqueous media. This phase transformation of CaPP in Hap resembled to the formation mechanism of Hap in animal organism.

• OSTI ID: 21000674
• Journal Information: Materials Research Bulletin, Vol. 42, Issue 7; Other Information: DOI: 10.1016/j.materresbull.2006.10.003; PII: S0025-5408(06)00398-9; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
APATITES
CALCIUM
CALCIUM HYDROXIDES
CALCIUM PHOSPHATES
CRYSTAL GROWTH
HYDRATES
PH VALUE
PHASE TRANSFORMATIONS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION