Phase diagram estimation of the Al2O3-SiO2-Re2O3 systems

Abstract

Nine limiting binaries of Al203-SiOz-Re203(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, liquidus surfaces and a series of isothermal sections of four ternaries 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. NotationAll quantities were restricted to one mole unless otherwise specified. G ~ °G~ Xl EG÷ ks AGf(i) AHf(i) ASf(i) °G~ ° G1-A~ % Gibbs free energy of ~ Phase Gibbs free energy of pure component i of ~ phase mole fraction of component i excess free energy of ~ phase j-th order parameter of Redlich-Kister polynomial fusion free energy of component i fusion enthalpy of component i fusion entropy of component i Gibbs free energy of pure component i of solid phase Gibbs free energy of pure Al203 of liquid phase Gibbs free energy of pure Al2Os of solid phase °G(Le~%)0.333(SiO2)0.6667 Gibbs free energy of stoichiometric phase ( La203 )0.333 ( SiO2 )0.6667 k31-(Sm2%)(A12% ) 3th order solution parameter of Redlich-Kister polynomial in Sm203 and A1203 binary

Liquid Regions of Lanthanum-Bearing Aluminosilicates

“…The oxyapatite phase is found in the La 2 O 3 -SiO 2 system [14]. The RE 2 O 3 -Al 2 O 3 -SiO 2 systems (RE = Nd, Sm, Gd and La) were computed by simplified thermodynamic properties associating with symmetric extrapolated expression [15][16][17].…”