CRYSTALLIZATION OF IRON PHOSPHATE-GLASSES

The crystallisation of xFe(2)O(3)(100-x)P2O5, (14 less than or equal t o x less than or equal to 40) glasses has been investigated by differe ntial thermal analysis, x-ray, diffraction analysis and Raman spectros copy. The glasses were heat treated in dry argon from 298 to 1143 K. T he crystallisation temperature and number of crystallised phases depen ded upon the glass composition, atmosphere and heat treatment temperat ure. With increasing Fe2O3 content the structure of phosphate glass ch anges from metaphosphate chain structures to the pyrophosphate and eve ntually, to orthophosphate structures. The relative amount of iron (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 ha ve the same basic phosphate structure.