Hydroxyapatite Formation from Octacalcium Phosphate and Its Related Compounds: A Discussion of the Transformation Mechanism
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- Yokoi Taishi
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University Materials Research and Development Laboratory, Japan Fine Ceramics Center
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- Goto Tomoyo
- The Institute of Scientific and Industrial Research, Osaka University
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- Kato Takeharu
- Nanostructures Research Laboratory, Japan Fine Ceramics Center
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- Takahashi Seiji
- Materials Research and Development Laboratory, Japan Fine Ceramics Center
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- Nakamura Jin
- Graduate School of Engineering, Nagoya University
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- Sekino Tohru
- The Institute of Scientific and Industrial Research, Osaka University
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- Ohtsuki Chikara
- Graduate School of Engineering, Nagoya University
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- Kawashita Masakazu
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University
Abstract
<p>Octacalcium phosphate (OCP), which has a layered structure composed of an apatitic layer and a hydrated layer, is a precursor of hydroxyapatite (HAp). Although the topotactic transformation of OCP to HAp is a well-known phenomenon, its mechanism remains unclear. In this study, to clarify the role of the OCP hydrated layer in the mentioned transformation, we investigated the behavior of the transformation of OCP with hydrated layers of different thicknesses to HAp under hydrothermal conditions. We used three types of samples: plain OCP (Pure-OCP), OCP with incorporated succinate ions (Suc-OCP), and OCP with incorporated suberate ions (Sub-OCP). We found that all three OCP types transformed topotactically into HAp. The order of reactivity was Sub-OCP > Suc-OCP > Pure-OCP, which corresponds to the thickness of the hydrated layer. Since the transformation involves a compositional change, our finding implies that the hydrated layer acts as a diffusion (mass transfer) passage for dicarboxylate ions and hydrogen phosphate ions located within it, which move outside the crystal during the topotactic transformation. Our results thus contribute to a better understanding of the topotactic transformation mechanism of OCPs to HAp.</p>
Journal
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- Bulletin of the Chemical Society of Japan
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Bulletin of the Chemical Society of Japan 93 (5), 701-707, 2020-05-15
The Chemical Society of Japan
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Details
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- CRID
- 1390566775134444544
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- NII Article ID
- 130007842951
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- ISSN
- 13480634
- 00092673
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- Text Lang
- en
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- Data Source
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- JaLC
- Crossref
- CiNii Articles
- KAKEN
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- Abstract License Flag
- Disallowed