Patent ID: 7674735

Claim:
A glass-ceramic seal composition, said composition being a boron-free glass-ceramic material consisting of: 30-50 wt. % SiO 2 , 2-8 wt. % Al 2 O 3 , 10-40 wt. % CaO, and at least one of 0-40 wt. % SrO, 0-35 wt. % BaO, 0-10 wt. % MgO; and optionally, at least one oxide selected from the group consisting of ZnO, Nb 2 O 5 , Ta 2 O 3 , La 2 O 3 , Y 2 O 3 , Sb 2 O 5 ; and transition metal oxides, and wherein the Σ MO , where M is one or more of Mg, Ca, Ba and Sr, is in the range of 40-60 wt. %, and when said optional oxide(s) is included in the composition, the amount of the oxide(s) selected is in the range of >0-8 wt. % for ZnO and transition metal oxides and >0-10% for Nb 2 O 5 , Ta 2 O 3 , La 2 O 3 , Y 2 O 3 , Sb 2 O 5 , and said composition is boron-free.