title: Crystallization behavior of silica-calcium phosphate biocomposites: XRD and FTIR studies.
abstract: Silica and calcium phosphates (CaP) are the most important ingredients in bioactive materials that bond to bone and enhance bone tissue formation. In this study, silica-calcium phosphate (SiO2-CaP) composites were developed by powder metallurgy method, using silica (SiO2) and anhydrous dicalcium phosphate (CaHPO4) powders (CaP) in the ratios (wt%): 20/80, 40/60, 60/40 and 80/20. The effects of temperature and chemical composition on crystallization and phase transformation of the SiO2-CaP composites were evaluated by XRD and FTIR. Thermal treatment of the starting material suggested that CaHPO4 transforms into: gamma-Ca2P2O7 at 800 degrees C; beta-Ca2P2O7 at 1000 degrees C and alpha-Ca2P2O7 at 1200 degrees C. On the other hand, beta-quartz was the only detected phase after thermal treatment of silica in the temperature range 800-1200 degrees C. For all SiO2-CaP composites, SiO2 and CaP did not modify the crystallization behavior of each other when sintered in the temperature range 800-1000 degrees C. However, at 1200 degrees C, CaP promoted the transformation of gamma-quartz into alpha-cristobalite. Moreover, SiO2 stabilized beta-Ca2P2O7. The modifications in the crystallization behavior were related to ion substitution and formation of solid solutions.
authors.affiliation: Center for Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: C Q
authors.initials: CQ
authors.lastname: Ning
authors.forename: Y
authors.initials: Y
authors.lastname: Greish
authors.forename: A
authors.initials: A
authors.lastname: El-Ghannam
mesh_terms: D018786:Bone Substitutes / Q000032:analysis / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D006358:Hot Temperature; D008420:Manufactured Materials / Q000032:analysis; D008422:Materials Testing / Q000379:methods*; D008968:Molecular Conformation; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; D012822:Silicon Dioxide; C020243:calcium phosphate