A transparent glass-ceramic composition including: of the formula Ta.sub.2-xAl.sub.xO.sub.5-x where x is less than 1; of the formula AlTaO.sub.4; of the formula AlPO.sub.4; a mixture of AlTaO.sub.4 and AlPO.sub.4; or a mixture of the formula Ta.sub.2-xAl.sub.xO.sub.5-x, AlTaO.sub.4, and AlPO.sub.4. Also disclosed are transparent glass-ceramic compositions including, for example, a dopant as defined herein, or a supplemental metal oxide or metalloid oxide of M.sub.xO.sub.y, M.sub.xM′.sub.xO.sub.y, or a mixture thereof such as oxides of Nb, Ti, W, B, or Ga, as defined herein. Also disclosed are methods of making the disclosed transparent glass-ceramic compositions, and optical articles, optical components, and optical apparatus thereof.

The invention relates to glass articles suitable for use as electronic device housing/cover glass which comprise a glass ceramic material. Particularly, a cover glass comprising an ion-exchanged glass ceramic exhibiting the following attributes (1) optical transparency, as defined by greater than 90% transmission at 400-750 nm; (2) a fracture toughness of greater than 0.6 MPa.Math.m.sup.1/2; (3) a 4-point bend strength of greater than 350 MPa; (4) a Vickers hardness of at least 450 kgf/mm.sup.2 and a Vickers median/radial crack initiation threshold of at least 5 kgf; (5) a Young's Modulus ranging between about 50 to 100 GPa; (6) a thermal conductivity of less than 2.0 W/m° C., and (7) and at least one of the following attributes: (i) a compressive surface layer having a depth of layer (DOL) greater and a compressive stress greater than 400 MPa, or, (ii) a central tension of more than 20 MPa.

A glass-ceramic that includes a first crystal phase including (Mg.sub.xZn.sub.1-x)Al.sub.2O.sub.4, where x is ≤1, and a second crystal phase including tetragonal ZrO.sub.2. The glass-ceramic may be substantially free of arsenic, tin, antimony, and cesium, each of the arsenic, tin, antimony, and cesium present at less than 0.01% (by mole of oxide). Further, the glass-ceramic may include a transmittance of at least about 80% to light having a wavelength of 380 nm to 760 nm.

ZrO.sub.2-toughened glass ceramics having high molar fractions of tetragonal ZrO.sub.2 and fracture toughness value of greater than 1.8 MPa.Math.m.sup.1/2. The glass ceramic may also include also contain other secondary phases, including lithium silicates, that may be beneficial for toughening or for strengthening through an ion exchange process. Additional second phases may also decrease the coefficient of thermal expansion of the glass ceramic. A method of making such glass ceramics is also provided.

Glass-ceramics and precursor glasses that are crystallizable to glass-ceramics are disclosed. The glass-ceramics of one or more embodiments include rutile, anatase, armalcolite or a combination thereof as the predominant crystalline phase. Such glasses and glass-ceramics may include compositions of, in mole %: SiO.sub.2 in the range from about 45 to about 75; Al.sub.2O.sub.3 in the range from about 4 to about 25; P.sub.2O.sub.5 in the range from about 0 to about 10; MgO in the range from about 0 to about 8; R.sub.2O in the range from about 0 to about 33; ZnO in the range from about 0 to about 8; ZrO.sub.2 in the range from about 0 to about 4; B.sub.2O.sub.3 in the range from about 0 to about 12, and one or more nucleating agents in the range from about 0.5 to about 12. In some glass-ceramic articles, the total crystalline phase includes up to 20% by weight of the glass-ceramic article.

An opaque gahnite-spinel glass ceramic is provided. The glass ceramic includes a first crystal phase including (Mg.sub.xZn.sub.1-x)Al.sub.2O.sub.4 where x is less than 1 and a second crystal phase includes at least one of tetragonal ZrO.sub.2, MgTa.sub.2O.sub.6, mullite, and cordierite. The glass ceramic has a Young's modulus greater than or equal to 90 GPa, and has a hardness greater than or equal to 7.5 GPa. The glass ceramic may be ion exchanged. Methods for producing the glass ceramic are also provided.

A black β-spodumene glass ceramic is provided. The glass ceramic includes β-spodumene as a primary crystal phase and gahnite as a minor crystal phase. The glass ceramic is characterized by the color coordinates: L*: 20.0 to 40.0, a*: −1.0 to 0.5, and b*: −5.0 to 1.0. The glass ceramic may be ion exchanged. Methods for producing the glass ceramic are also provided.

A glass-ceramic includes a silicate-containing glass and crystals within the silicate-containing glass. The crystals include non-stoichiometric tungsten and/or molybdenum sub-oxides, and the crystals are intercalated with dopant cations.

Embodiments of a glass-ceramic, glass-ceramic article or glass-ceramic window that includes 40 mol %≤SiO.sub.2≤80 mol %; 1 mol %≤AI.sub.2O.sub.3≤15 mol %; 3 mol %≤B.sub.2O.sub.3≤50 mol %; 0 mol %≤R.sub.2O≤15 mol %; 0 mol %≤RO≤2 mol %; 0 mol %≤P.sub.2O.sub.5≤3 mol %; 0 mol %≤SnO.sub.2≤0.5 mol %; 0.1 mol %≤MoO.sub.3≤15 mol %; and 0 mol %≤WO.sub.3≤10 mol % (or 0 mol %<MoO.sub.3≤15 mol %; 0.1 mol %≤WO.sub.3≤10 mol %; and 0.01 mol %≤V.sub.2O.sub.5≤0.2 mol %), wherein the WO.sub.3 (mol %) plus the MoO.sub.3 (mol %) is from 1 mol % to 19 mol %, and wherein R.sub.2O (mol %) minus the AI.sub.2O.sub.3 (mol %) is from −12 mol % to 4 mol %, are disclosed.

Al.sub.2O.sub.3— rich compositions with desirable hardness and crack resistance for various functional applications. Also disclosed is a method of manufacturing the composition into various dimensions and shapes under a temperature much lower than in conventional methods.