Thermochemie des Systems MgO—B₂O₃

Thermodynamic assessment of B2O3–MgO binary system

“…Furthermore, considering the uncertainty in experimental results given in Refs. [28,30,31], and experimental difficulties at high temperatures, the correlation between experimental and calculated activities of MgO and the enthalpy of formation of the solid phases is acceptable.…”

“…Hauck et al [28] measured the chemical potential of MgO as a function of the composition referred to pure solid MgO, by the EMF-technique using cells with MgF 2 as fluorine-ion conducting electrolyte at 1173 K. Based on their experimental results, the Gibbs energy of formation G f 0 Δ referred to solid MgO of the following stoichiometric solid compounds was estimated on the assumption that the enthalpy of formation of these magnesium borate compounds are approximately independent of temperature in the range from about 900 to 1300 K: …”

“…Based on the measurements of chemical potential of MgO, both the Gibbs energy and entropy of formation of the magnesium borate compounds at 1173 K and 973 K have been calculated by Hauck et al [28].…”

“…summarizes the published thermodynamic data and stability ranges for equilibrium phases of the B 2 O 3 -MgO system[14][15][16][17]23,[25][26][27][28][29][30][31][32][33][34][35]. The crystallographic information of the stable solid magnesium borate phases with different MgO:B 2 O 3 ratios included in the system MgO-B 2 O 3[23,[36][37][38][39][40][41] is given inTable 2.3.…”

Thermodynamic analysis and experimental studies of magnesium extraction from szaibelyite-suanite ore by aluminium

“…The existence of 3MgO·B 2 O 3 proves that a reaction between MgO and 2MgO·B 2 O 3 occurred: [5] According to Hauck and Muller (1979), the formation of 3MgO·B 2 O 3 occurs easily at high temperatures, and the standard Gibbs free energy G 0 (in kJ mol −1 ) for Equation [5] can be calculated by…”