Estimation of Solid Phase Relationship in the Al_2O_3-SiO_2-Re_2O_3 Systems

摘要

Nine limiting binaries of A12O3-SiO2- Re2O3 (Re=Nd, Sm, Gd and La) system are assessed. The binary diagrams or experimental information from Toropov, Mizuno, Aramaki, Bondar, Rolin and Coutures are optimized with the substitutional model of Kaufman and Nesor and the approximate formula of fusion free energy for rare earth element oxides of Wu and Pelton. The extracted Gibbs free energies of pure solid oxides and stoichiometric phases and the solution parameters are used to estimate the corresponding binaries, and a series of isothermal sections of four ternaries Al2O,-SiO2-Nd2O3, A12O3-SiO2-SiO2O3 , A12O3-SiO2-Gd2O3 and A12O3-SiO2-La2O3. In the Al2O3-SiO2-Gd2O3 system samples as fired at exact temperature with different compositions were analyzed by x-ray diffractometer and the detected results are fitted with the calculation of isothermal sections.