Liquidus Surfaces and Isothermal Section at 973 K of the BaO-ZnO-B<SUB>2</SUB>O<SUB>3</SUB> Pseudo-Ternary System

Abstract

The liquidus surfaces and the isothermal section at 973 K of the pseudo-ternary BaO-ZnO-B 2 O 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 5ZnOÁ2B 2 O 3 extends long and narrow toward BaOÁB 2 O 3 . The slope of the liquidus surface in equilibrium with ZnO is steep in the region of less than 20 mol%B 2 O 3 but gentle when the B 2 O 3 content exceeds 20 mol%. The liquidus surface in equilibrium with 3BaOÁB 2 O 3 widely extends and its slope is gentle in the region of less than 30 mol%B 2 O 3 but steep when the B 2 O 3 content exceeds 30 mol%. Pseudo-ternary BaO-ZnO-B 2 O 3 compounds were not found in the composition range investigated. The ternary eutectic reactions are as follows: L ! 3BaOÁB 2 O 3 þ BaOÁB 2 O 3 þ ZnO, occurring at 1033 K at the composition 46.5 mol%BaO-14.5 mol%ZnO-