Corning Incorporated
Glasses and glass ceramics including a metal oxide concentration gradient

Abstract:

A glass-based article may include from about 45 mol. % to about 80 mol. % SiO.sub.2; from about 0 mol. % to about 10 mol. % Na.sub.2O; less than about 5 mol. % K.sub.2O; a non-zero amount of Al.sub.2O; and an amorphous phase and a crystalline phase. The article may further in include a stress profile comprising a surface compressive stress (CS) and a maximum central tension (CT). A ratio of Li.sub.2O (mol. %) to R.sub.2O (mol. %) in the article is from about 0.5 to about 1, where R.sub.2O is the sum of Li.sub.2O, Na.sub.2O, and K.sub.2O in the article. CT may be greater than or equal to about 50 MPa and less than about 100 MPa. CS may be greater than 2.0CT. A depth of compression (DOC) of the stress profile may be greater than or equal to 0.14t and less than or equal to 0.25t, where t is the thickness of the article.