Crystallisation of Iron Phosphate Glasses

The crystallisation of xFe 2 O 3 (100-x)P 2 O 5 , (14≤x≤40) glasses has been investigated by differential thermal analysis, x-ray diffraction analysis and Raman spectroscopy. The glasses were heat treated in dry argon from 298 to 1143 K. The crystallisation temperature and number of crystallised phases depended upon the glass composition, atmosphere and heat treatment temperature. With increasing Fe 2 O 3 content the structure of phosphate glass changes from metaphosphate chain structures to the pyrophosphate and eventually to orthophosphate structures. The relative amount ofiron (II) and iron(III) present during the crystallisation process was found to have a significant effect on the resulting crystalline phases. The results suggest that the glass and its crystalline counterpart both have the same basic phosphate structure.