Preparation and structural study of binary phosphate glasses with high calcium and/or magnesium content

摘要

Glasses of high CaO or MgO content in the systems xCaO(1 - x)P2O5 (0.50 less than or equal to x less than or equal to 0.72) and xMgO(1 - x)P2O5 (0.50 less than or equal to x less than or equal to 0.80) have been prepared for the first time using a twin roller device and studied by Raman spectroscopy. It has been shown that the structure of glasses depends on the type of alkali earth cation; the modification of the phosphate network is higher for the Ca containing glasses with respect to the Mg ones, at the same alkali earth content, due to the well defined Ca properties as a modifying cation. X-ray diffraction patterns of the thermally treated at 850 degreesC calcium containing glasses show precipitation of bioactive crystalline phases, such as beta-Ca-3(PO4)(2) and beta-Ca2P2O7. The molecular dynamics simulations have provided insight for the high Mg and Ca content phosphate glasses formation, where their average oxygen coordination number is calculated as five and six for all glass compositions studied, respectively. (C) 2004 Elsevier B.V. All rights reserved.