TY - JOUR
T1 - Changes in crystalline properties of nanosized hydroxyapatite powders prepared by low-temperature reactive crystallization
AU - Kim, Woon Soo
AU - Kim, Woo Sik
AU - Hirasawa, Izumi
PY - 2002/11/1
Y1 - 2002/11/1
N2 - In the reactive crystallization of hydroxyapatite (HAP) done with CaCl2, KH2PO4 and NaOH solutions at the reaction temperature of 60°C in a semi-batch reactor, the relationship of the crystalline properties of nanosized HAP powders with the operational conditions was experimentally investigated. The crystallinity of needle-like HAP powders was enhanced with decreasing OH- ion composition and reactants concentration, which corresponded well with the increase in the crystal size, but had nothing to do with the aging of the product suspension. Even though the supersaturation level was predicted not to be influenced by the OH- ion composition, the crystal growth of the HAP powders was striking at low OH- ion composition, thereby resulting in larger HAP with high crystallinity. Comparing the growth orientation of the HAP powders before and after sintering, the crystal growth was preferentially promoted on the face of (002) in the direction of the crystallographic c-axis, especially at low OH- ion composition and reactants concentration during the crystallization, and it was transferred on the (300) face along the a-axis after sintering at 1000°C for 3 h, which seem to be caused by the unbalanced grain coalescing according to the crystallographic axes of HAP.
AB - In the reactive crystallization of hydroxyapatite (HAP) done with CaCl2, KH2PO4 and NaOH solutions at the reaction temperature of 60°C in a semi-batch reactor, the relationship of the crystalline properties of nanosized HAP powders with the operational conditions was experimentally investigated. The crystallinity of needle-like HAP powders was enhanced with decreasing OH- ion composition and reactants concentration, which corresponded well with the increase in the crystal size, but had nothing to do with the aging of the product suspension. Even though the supersaturation level was predicted not to be influenced by the OH- ion composition, the crystal growth of the HAP powders was striking at low OH- ion composition, thereby resulting in larger HAP with high crystallinity. Comparing the growth orientation of the HAP powders before and after sintering, the crystal growth was preferentially promoted on the face of (002) in the direction of the crystallographic c-axis, especially at low OH- ion composition and reactants concentration during the crystallization, and it was transferred on the (300) face along the a-axis after sintering at 1000°C for 3 h, which seem to be caused by the unbalanced grain coalescing according to the crystallographic axes of HAP.
KW - Crystallinity
KW - Crystallite size
KW - Hydroxyapatite
KW - Reactive crystallization
KW - Sintering
KW - Supersaturation level
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U2 - 10.1252/jcej.35.1203
DO - 10.1252/jcej.35.1203
M3 - Article
AN - SCOPUS:0036871904
VL - 35
SP - 1203
EP - 1210
JO - Journal of Chemical Engineering of Japan
JF - Journal of Chemical Engineering of Japan
SN - 0021-9592
IS - 11
ER -