Raman imaging as a useful tool to describe crystallization of aluminum/iron-containing polyphosphate glasses

Abstract

Polyphosphate glasses are materials of a wide spectrum of applications in many fields. The subject of the work is polyphosphate glasses containing aluminum and iron. Three compositions of the glasses were obtained and the materials have been characterized in terms of their crystallization. The differences in crystallization behavior between powder and bulk materials were compared. The crystallized materials were analyzed by Raman scattering spectroscopy and X-ray diffraction method. It was evidenced that depending on the glass composition the main crystalline phases were Al(PO3)3, AlPO4, FePO4, Fe3(P2O7), Fe4(P2O7)3, FePO4. The glass crystallization leads to enrichment of the residual glassy phase in P2O5 and increases its polymerization. Thus, it was observed the glass inhomogeneities are being increased due to crystallization. The two dimensions spectral maps of the bulk crystallized samples were executed to describe the mechanism and type of crystallization. The depth profiling proves the differences between surface and interior phase composition.