Abstract: Phosphorus-containing silicate opal glasses were prepared by means of conventional melt quenching technology, and opaque mechanism and microstructure of the glasses were investigated by XRD,SEM and EDS methods.The influence of R_2O_3(R=Al or B) content on the microstructure and the thermal expansion coefficient was investigated. The results show that heavy opaque glasses are obtained due to the addition of P_2O_5, and this is results from unstable disassemble phase separation; with substituting 3wt%B_2O_3 for Al_2O_3, traces of unknown crystals are precipitated and particles size becomes inhomogenous, and thermal expansion coefficient increases greatly.

Key words: opal glass;phase separation;microstructure;thermal expansion coefficient