Phase Equilibria in the Fe₂O₃-P₂O₅ System
Four ferric phosphate compounds were identified in the Fe2O 3-P2O5 system and the liquidus surfaces in the subsystems Fe3PO7-FePO4, FePO 4-Fe4(P2O7)3, and Fe 4(P2O7)3-Fe(PO3) 3 were determined. The results are significantly different from those presented by Wentrup in 1935. Fe3PO7 is the stable ferric oxophosphate compound, not Fe4P2O11, and Fe3PO7 decomposes in air at 1090°C. The congruent melting point of FePO4 (1208°C) is similar to what was reported, but Fe4(P2O7)3 melts congruently at 945°C, about 300°C lower than claimed by Wentrup. Fe(PO 3)3, for which the melting temperature has not been previously reported, melts congruently at 1205°C. Eutectic points exist at 58.0 mol% Fe2O3 (1070°C), 42.7% Fe2O 3 (925°C), and 37.0% Fe2O3 (907°C). The latter two eutectic points bracket the conventional glass-forming range for iron phosphate melts under consideration as alternative hosts for nuclear wastes. © 2011 The American Ceramic Society.
L. Zhang et al., "Phase Equilibria in the Fe₂O₃-P₂O₅ System," Journal of the American Ceramic Society, American Chemical Society (ACS), Jan 2011.
The definitive version is available at http://dx.doi.org/10.1111/j.1551-2916.2010.04287.x
Materials Science and Engineering
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© 2011 American Chemical Society (ACS), All rights reserved.