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Synthesis of calcium phosphate crystals in a silica hydrogel containing phosphate ions

Published online by Cambridge University Press:  31 January 2011

Taishi Yokoi*
Affiliation:
Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
Masakazu Kawashita
Affiliation:
Department of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8579, Japan
Chikara Ohtsuki
Affiliation:
Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

Calcium phosphate crystals were synthesized by diffusing calcium ions into silica hydrogels containing phosphate ions. Hydroxyapatite [HAp, Ca10(PO4)6(OH)2] and octacalcium phosphate [OCP, Ca8(HPO4)2(PO4)4.5H2O] with different types of crystal morphology were formed in the gel. The HAp had an irregular or rod shape, a few micrometers in length, while the OCP had an irregular, spherulite, rod- or ribbonlike shape, ranging in size from a few micrometers to several tens of micrometers, depending on the amount of phosphoric acid added and the reaction temperature. The morphology of the OCP changed from an irregular shape to a ribbonlike or rod shape, via a spherulite shape, depending on the amount of phosphoric acid added and the reaction temperature. The degree of supersaturation of the reaction environment and the rate-determining step in the HAp and OCP crystal growth mechanism have been ascribed to the changes in crystal morphology of the HAp and OCP.

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Articles
Copyright
Copyright © Materials Research Society 2009

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