Liquidus Surfaces and Isothermal Section at 973 K of the BaO-ZnO-B_2O_3 Pseudo-Ternary System

摘要

The liquidus surfaces and the isothermal section at 973 K of the pseudo-ternary BaO-ZnO-B_2O_3 system were determined using the thermal analysis and X-ray diffraction. The liquidus surface in equilibrium with ZnO spreads over a wide composition range and that in equilibrium with 5ZnO centre dot 2B_2O_3 extends long and narrow toward BaO-B_2O_3. The, slope of the liquidus surface in equilibrium with ZnO is steep in the region of less than 20mol percent B_2O_3 but gentle when the B_2O_3 content exceeds 20mol percent. The liquidus surface in equilibrium with 3BaOB_2O_3 widely extends and its slope is gentle in the region of less than 30mol percent B_2O_3 but steep when the B_2O_3 content exceeds 30mol percent. Pseudo-ternary BaO-ZnO-B_2O_3 compounds were not found in the composition range investigated. The ternary eutectic reactions are as follows: L -- >3BaO centre dot B_2O_3 + BaOB_2O_3 + ZnO, occurring at 1033 K at the composition 46.5mol percent BaO-14.5mol percent ZnO-39.0mol percent B_2O_3, L -- > BaO centre dot B_2O_3 + ZnO-B_2O_3 + 5ZnO centre dot 2B_2O_3, occurring at 1038K at the composition 34mol percent BaO-21mol percent ZnO-45mol percent B_2O, L -- > BaO-2B_2O_3 + BaO-4B_2O_3 + ZnO-B_2O_3, occurring at 1008K at the composition 19mol percent BaO-17mol percent ZnO-64mol percent B_2O_3.