The SiO2–P2O5 binary system: New data concerning the temperature of liquidus and the volatilization of phosphorus

Abstract The SiO 2 –P 2 O 5 binary systemis not well known. The aim of this work is to enhance the description of this quasibinary system. Volatilization of phosphorus, liquidustemperatures and phases crystallization were studied by TGA, X-ray diffraction, NMR and SEM after quenching systems of two compositions (50 wt% SiO 2 –50 wt% P 2 O 5 and 75 wt% SiO 2 –25 wt% P 2 O 5 ). At high temperature (>950 °C), volatilization of phosphorus in the SiO 2 –P 2 O 5 binary systemoccurs. The liquidustemperatures are close to the ones proposed in the literature. The experimental results show the crystallization of SiP 2 O 7 in four different polymorphs and the formation of the Si 5 O(PO 4 ) 6 oxide phase.