The solid solubility of Sc2O3, Al2O3, Cr2O3, SiO2 and ZrO2 in MgO

Abstract Scanning electron microscopy and X-ray diffraction lattice parameter measurements have been used to determine the extent of solid solubility of oxides in MgO. The solubility of Sc2O3 ranges between 0.005 and 0.044 mole fraction in the temperature interval from 1270°C to 1600°C, with an experimental heat of solution equalling 36.8 kcal/mole. Cr2O3 has a similar solubility range, between 0.007 and 0.038 mole fraction in the temperature interval from 1200°C to 1600°C, and the heat of solution was determined to be 43.6 kcal/mole. Much smaller solubility was found for Al2O3, between 0.004 and 0.007 mole fraction in the temperature interval from 1200°C to 1600°C, and the heat of solution was 97.2 kcal/mole. The solubility of SiO2 is less than 0.00034 mole fraction at 1850°C and the solubility of ZrO2 is less than 0.000075 mole fraction at 1885°C.