Phase relationship in the system MgO-V2O3 between 1661 and 1873 K at PO2=(3.55±0.2)×10-6 and (3.55±0.3)×10-5 Pa

• Published in: Calphad 2020-09, Vol.70, p.101777, Article 101777
• Main Authors: Vickerfält, Amanda, Martinsson, Johan, Yan, Baijun, Sichen, Du
• Format: Article
• Language: English
• Subjects: Composition; Electron probe microanalysis; Magnesium oxide; MgO; Oxygen; Oxygen potential; Phase relationship; Quenching; Solubility; Spinel; Temperature; V2O3; Vanadium oxides
• ISSN: 0364-5916; 1873-2984
• DOI: 10.1016/j.calphad.2020.101777

The composition ranges of the phases in the pseudo binary system MgO-V2O3 were studied between 1661 and 1873 K and at controlled oxygen partial pressures of (3.55 ± 0.2) × 10-6 and (3.55 ± 0.3) × 10-5 Pa. The phase relationship was determined by equilibrating MgO-V2O3 pellets in a CO-CO2 mixture followed by quenching and electron-probe microanalysis. To ensure sufficient quenching, a new setup was designed and developed, so that the equilibrated samples can be quenched in oil directly under the same atmosphere inside the experimental setup. Three different phases were found in the samples, namely MgO, MgO-V2O3 spinel and V2O3. The phase boundaries were determined with good reproducibility. The solubility of V2O3 in the MgO phase increased with temperature and was significantly higher than literature data. The spinel as well as the V2O3 composition range were found to change only a little with temperature in the investigated temperature range. Decreased oxygen potential led to a slight increase of the V2O3 content in the spinel phase and V2O3 phase. Furthermore, decreased oxygen potential resulted in a significant increase of the solubility of V2O3 in the MgO phase at the higher temperatures, especially at 1873 K. •Control of pO2 during quenching is essential for the study of phase boundaries in systems containing multi-valent oxides.•The extension of the spinel phase and the V2O3 phase is only a little affected by temperature in the range 1661-1873 K.•The solubility of V2O3 in MgO phase increases markedly with temperature in the range 1661-1873 K.•The V2O3 content in the spinel phase and the V2O3 phase is a little higher at the lower pO2.•The solubility of V2O3 in MgO phase is markedly increased by decreased pO2 in the upper temperature range.