| abstract |
A glass plate having the following composition: 70% ≦ SiO 2 ≦ 85%, 0.0% ≦ Al 2 O 3 ≦ 10%, 0.0% ≦ B 2 O 3 ≦ 15%, 1.5% ≦MgO ≦ 20%, 0.0% ≦ CaO ≦ 20%, 0.0% ≦ SrO ≦ 5.0%, 0.0% ≦ BaO ≦ 1.0%, 0.0% ≦ ZnO ≦ 5.0%, 1.0% ≦ Li 2 O ≦ 11%, 0.0% ≦ Na 2 O ≦ 10%, 0.0% ≦ K 2 O ≦ 10%, 3.0% ≦ R 2 O ≦ 11%, 0.01% ≦ Fe 2 O 3 ≦ 1.00% and 2.0% ≦ RO ≦ 20%, and having the following properties: T 2 ≦ 1650°C, T 12 ≦ 730°C, ε r ≦ 6.5 and tanδ ≦ 0.0090. |