Phase Equilibria and Crystallization of Melts in the System Na 2 O‐BaO‐SiO 2

Phase‐equilibrium studies of the liquidus surface of the Na 2 O‐BaO‐SiO 2 system are presented. The system contains 5 ternary compounds, Na 2 Ba 4 Si 10 O 25 , Na 2 Ba 4 Si 2 O 6 , Na 2 Ba 2 Si 2 O 7 , X (probably Na 2 Ba 18 Si 28 O 75 ), and Y (probably Na 2 Ba 45 Si 73 O 192 ), all of which melt incongruently. Twenty‐three liquidus invariant points, including 13 peritectics, 4 eutectics, and 6 thermal maxima, were located. Metastable crystallization reactions are commonly encountered, and some of the metastable equilibria are described.