Biphasic calcium phosphate (BCP) particle consisting of -tricalcium phosphate and tetracalcium phosphate was synthesized from calcium carbonate and calcium hydrogen phosphate. The Ca/P molar ratio of the product was 1.80. Uni-morphologically controlled BCP particles were synthesized without mixing.
The evaluation of powder properties and the examination based on ISO 13779-3 and JIS T 0330-3 for calcium phosphates as biomaterial were performed. Powder properties were investigated by X-ray diffractometry (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), measurement of specific surface area (SSA), particle size analysis and chemical analysis. Crystalline content and chemical impurities were evaluated by the examination based on ISO 13779-3, and the solubility was evaluated by the examination based on JIS T 0330-3. These results indicated that our products were single phase, and crystalline content and chemical impurities were within the range of specification. Moreover, it was found that hydroxyapatite has different characteristics for particle morphology and SSA according to the difference of synthesis methods. It was comfirmed that the elution amounts of calcium (Ca 2+ ) ion per each specific surface area were different among our products from the examination of solubility. Consequently, these products are expected as raw materials for biomaterials, and the requiered products will be supplied by the application of our technology.
Hydroxyapatite (HAP), as one of the most well-known functional ceramic materials, has attract much attention due to its excellent biocompatibility, ion-exchange ability and adsorption property. By taking advantages of the thermally induced active radicals and unique basic/acidic sites exist on surface of HAP, we've succeeded in observing complete decomposition of volatile organic compound (VOC) on HAP which makes it became the most promising noble-metal-free catalyst for VOC controlling and environmental cleaning. In present work, four types of HAPs with altered particle size, morphology, crystallinity and chemical structures were synthesized by utilizing different calcium and phosphorus precursors and altered approaches. With detailed characterizations of obtained HAPs via scanning electron microscopy, powder X-ray diffraction, Fourier-transform infrared microscopy, surface acidity/basicity analysis through NH 3 /CO 2 adsorption, the influence of precursors and approaches during synthesis stage on later catalytic activity of HAPs for oxidative decomposition of ethyl acetate is systemically investigated in advance. It was found that the chemical structure tailored during synthesis stage plays an important role in deciding the surface basicity/acidity in obtained HAPs. The resultant HAP with harvested surface basic sites shows better catalytic activity in conversing ethyl acetate into CO 2 /CO, while HAP with larger number of acidic sites promotes the generation of organic product of ethylene. The contents in this work provide principal information for design and development of functional ceramic material.
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