2001/01/01 by Peter Schmid-Beurmann, Peter Schmid‐Beurmann
Chemistry · Engineering · Environmental Science · #Chemical Synthesis and Characterization #Metal Extraction and Bioleaching #Radioactive element chemistry and processing
paper · doi:10.1039/b006566h
openalex publication_date 2001/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
The phase relations in the quaternary system FeO–Fe2O3–P2O5–H2O were investigated under hydrothermal conditions at 386 and 586 °C at a pressure of 0.3 GPa. Under these conditions a restricted solid solution series coexists with the H2O bearing fluid phase between the Fe2(PO4)O and Fe4(PO4)3(OH)3 compositions. The members of this solid solution series were found to be isotypic to tetragonal β-Fe2(PO4)O. At 586 °C the composition of this series covers the range between 0.18 ≤ x ≤ 0.60 according to a stoichiometry of Fe3+4 − xFe2+3x(PO4)3(OH)3 − 3xO3x. With decreasing temperature this compositional range is reduced to compositions between 0.52 ≤ x ≤ 0.58. At 586 °C the Fe2(PO4)Oss solid solution series was found to coexist with hematite (Fe2O3), sarcopside (Fe3(PO4)2), Fe7(PO4)6 and monoclinic Fe4(PO4)3(OH)3 whereas at 386 °C they coexist with α-Fe2O3 (hematite), Fe3(PO4)2 (sarcopside), Fe7(PO4)6 and Fe3(PO4)2(OH)2 (barbosalite). The synthesis runs with the same compositions and P–T conditions but different starting compounds yielded a nearly phase pure member of the Fe2(PO4)Oss solid solution series. Therefore these results support the assumption that the Fe2(PO4)Oss solid solution is a stable product under the applied hydrothermal conditions.