On the phase diagram of the binary system Sc2O3-ScF3 in the temperature range 1400-1840 K

Article abstract of DOI:10.1016/0040-6031(95)02788-2

The phase diagram of the binary system Sc₂O₃-ScF₃ was investigated in the temperature range 1400-1840 K by quantitative differential thermal analysis (DTA). X-ray powder diffraction analysis revealed that at room temperature only the well-known compounds Sc₂O₃, ScOF and ScF₃ exist. At 1419 ± 3 K, the slightly non-stoichiometric compound of composition Sc(O,F)_1.88±δ is probably formed by eutectoid reaction from Sc₂O₃ and ScOF. ScOF decomposes into Sc(O,F)_1.88±δ(s) and ScF3(s) at 1460±3 K. Eutectic melting occurs at 1627 ± 3 K for a mixture of 67 mol% ScF₃ and 33 mol% ScO_1.5. Pure ScF₃ melts at 1822±3 K and does not display any solid state phase transition. The compound Sc(O,F)_1.88±δ could not be quenched to room temperature, and therefore structural details of this presumably fluorite-related phase could not be investigated.