CPC C03C 10/0027 (2013.01) [C03C 4/02 (2013.01); C03C 10/0036 (2013.01); C03C 21/002 (2013.01); C03C 21/005 (2013.01)] | 18 Claims |
1. A glass-ceramic article comprising:
a composition at a center-volume comprising, on an oxide basis:
55-75 mol % SiO2;
0.2-10 mol % Al2O3;
0-5 mol % B2O3;
15-30 mol % Li2O;
0-2 mol % Na2O;
0-2 mol % K2O;
0-5 mol % MgO;
0-2 mol % ZnO;
0.2-3.0 mol % P2O5;
0.1-10 mol % ZrO2;
0-4 mol % TiO2; and
0-1.0 mol % SnO2;
wherein (i) lithium disilicate and (ii) either β-spodumene or β-quartz are the two predominant crystalline phases (by weight) of the glass-ceramic article;
wherein the glass-article further comprises tetragonal ZrO2 as a crystalline phase; and
wherein one of the following is true: (i) the composition of the glass-ceramic article from a primary surface into a thickness of the glass-ceramic article comprises over 10 mol % Na2O, with the mole percentage of Na2O decreasing from the primary surface towards the center-volume (ii) the mole percentage of Na2O within the glass-ceramic article decreases as a function of depth into the thickness of the glass-ceramic article from the primary surface, with the maximum mole percentage of Na2O at any depth being 7 mol % Na2O, and sodium ions are present within the glass-ceramic article to a depth of at least 15 percent of the thickness from the primary surface.
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