A linear empirical correlation was established between Raman stretching wavenumbers of phosphorus–oxygen bonds and their bond lengths in inorganic crystalline phosphates. Although established on samples of inorganic crystalline phosphates, the correlation can be applied to glassy and amorphous phosphate materials (GAMs). Their unpolarized vibrational spectra are often similar because they are determined largely by short-range order. The correlation was used to predict PO bond length in the α-form of Li3PO4, which is stable over only a small range of temperatures below the melting-point. It can also be used to estimate the length of PO single bonds, terminal PO and OPO chain bonds and terminal double bonds in many technologically important amorphous materials containing phosphate groups. This correlation is expected to offer invaluable insight into the structures of phosphate species for which diffraction or other spectroscopic techniques provide incomplete structural information. That would enhance the value of Raman spectroscopy as a complementary technique in structural studies of phosphates. Copyright © 2004 John Wiley & Sons, Ltd.

Correlation between Raman wavenumbers and P?O bond lengths in crystalline inorganic phosphates

New macroporous calcium phosphate glass ceramic for guided bone regeneration

In vitro degradation behavior of a novel bioresorbable composite material based on PLA and a soluble CaP glass

The Raman spectrum of α-zinc pyrophosphate

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: y-Ca2P2O7 at 800°C; p-Ca2P2O7 at 1000°C and a-Ca2P2O7 at 1200°C. On the other hand, P-quartz was the only detected phase after thermal treatment of silica in the temperature range 800-1200 °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°C. However, at 1200°C, CaP promoted the transformation of p-quartz into a-cristobalite. Moreover, SiO2 stabilized p-Ca2P2O7. The modifications in the crystallization behavior were related to ion substitution and formation of solid solutions.

B.C. Cornilsen

Papers

The vibratonal spectra of β-Ca2P2O7 and γ-Ca2P2O7