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Conversion of amorphous tricalcium phosphate into apatitic tricalcium phosphate
Calcified Tissue International
|January 1, 1982
Summary
Amorphous tricalcium orthophosphate rapidly forms in supersaturated solutions. Upon hydrolysis, it transforms into a series of tricalcium orthophosphates and then apatitic phosphate, with distinct endothermic and exothermic reactions.
Area of Science:
- Materials Science
- Inorganic Chemistry
- Biomineralization
Background:
- Calcium orthophosphates are crucial in biological systems and industrial applications.
- Understanding the phase transformations of calcium phosphates is key to controlling their properties.
Purpose of the Study:
- To investigate the preparation and transformation of amorphous tricalcium orthophosphate.
- To characterize the hydrolysis and conversion processes of this material.
Main Methods:
- Rapid precipitation of calcium orthophosphate from highly supersaturated solutions at controlled pH.
- Monitoring hydrolysis and conversion using chemical analysis and thermal analysis (calorimetry).
Main Results:
- Amorphous tricalcium orthophosphate (Ca9(PO4)6, nH2O) was rapidly synthesized at pH 9-11.
- Hydrolysis yielded a series of tricalcium orthophosphates (Ca9(HPO4)x(PO4)6-x(OH)x) with simultaneous endothermic effects.
- Conversion to apatitic phosphate occurred at half hydrolysis with an exothermic effect.
Conclusions:
- The study elucidates the hydrolysis pathway of amorphous tricalcium orthophosphate.
- Phase transitions are accompanied by measurable thermal events, providing insights into reaction energetics.