Phase Equilibria in the Iron Oxide‐Cobalt Oxide‐Phosphorus Oxide System

Abstract

Solid‐state equilibria at 1000°C were determined in the Fe 2 O 3 ‐FePO 4 ‐Co 3 (PO 4 ) 2 ‐CoO area of the Fe‐Co‐P‐O system in air. Two new ternary compounds were observed: CoFe(PO 4 )O, an oxyphosphate which melts incongruently at 1130°C, and Co 3 Fe 4 (PO 4 ) 6 , an orthophosphate which melts incongruently at 1080°C. The ramifications of the liquidus behavior for the formation of rapidly solidified cobalt ferrite from cobalt ferrite‐phosphate melts are discussed.