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Phase Equilibria in the Fe 2 O 3 –P 2 O 5 System
Author(s) -
Zhang Liying,
Schlesinger Mark E.,
Brow Richard K.
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.04287.x
Subject(s) - phase (matter) , materials science , mineralogy , geology , chemistry , organic chemistry
Four ferric phosphate compounds were identified in the Fe 2 O 3 –P 2 O 5 system and the liquidus surfaces in the subsystems Fe 3 PO 7 –FePO 4 , FePO 4 –Fe 4 (P 2 O 7 ) 3 , and Fe 4 (P 2 O 7 ) 3 –Fe(PO 3 ) 3 were determined. The results are significantly different from those presented by Wentrup in 1935. Fe 3 PO 7 is the stable ferric oxophosphate compound, not Fe 4 P 2 O 11 , and Fe 3 PO 7 decomposes in air at 1090°C. The congruent melting point of FePO 4 (1208°C) is similar to what was reported, but Fe 4 (P 2 O 7 ) 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% Fe 2 O 3 (1070°C), 42.7% Fe 2 O 3 (925°C), and 37.0% Fe 2 O 3 (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.