A cover member includes at least a chemically strengthened glass. The chemically strengthened glass has a Young's modulus of 60 GPa or higher. The chemically strengthened glass includes a first surface and a second surface facing the first surface. The chemically strengthened glass has a thickness t of 0.4 mm or less.

Borate-glass biomaterials comprising: aNa.sub.2O. bCaO. cP.sub.2O.sub.5. dB.sub.2O.sub.3 wherein a is from about 1-40 wt %, b is from about 10-40 wt %, c is from about 1-40 wt %, and d is from about 35-80 wt %; and wherein the biomaterial has a surface area per mass of more than about 5 m.sup.2/g. Methods of making and uses of these biomaterials.

The present application provides LAS type transparent glass-ceramics of β-quartz of composition containing a high content of zinc, articles constituted at least in part of said glass-ceramics, glasses precursors of said glass-ceramics (with a low viscosity at high temperature), and also a method of preparing said articles. Said glass-ceramics present a composition, free of arsenic oxide and antimony oxide, except for inevitable traces, expressed as percentages by weight of oxides, containing: 64.5% to 66.5% of SiO.sub.2; 19.0% to 20.6% of Al.sub.2O.sub.3; 3.0% to 3.6% of Li.sub.2O; 0 to 1% of MgO; 1.7% to 3.4% of ZnO; 2% to 3% of BaO; 0 to 3% of SrO; 0 to 1% of CaO; 2% to 4% of TiO.sub.2; 1% to 2% of ZrO.sub.2; 0 to 1% of Na.sub.2O; 0 to 1% of K.sub.2O; with Na.sub.2O+K.sub.2O+BaO+SrO+CaO≤6%; optionally up to 2% of at least one fining agent comprising SnO.sub.2; and optionally up to 2% of at least one coloring agent.

A glass-ceramic article comprises: a center-volume composition comprising (on an oxide basis): 55-75 mol % SiO.sub.2; 0.2-10 mol % Al.sub.2O.sub.3; 0-5 mol % B.sub.2O.sub.3; 15-30 mol % Li.sub.2O; 0-2 mol % Na.sub.2O; 0-2 mol % K.sub.2O; 0-5 mol % MgO; 0-2 mol % ZnO; 0.2-3.0 mol % P.sub.2O.sub.5; 0.1-10 mol % ZrO.sub.2; 0-4 mol % TiO.sub.2; and 0-1.0 mol % SnO.sub.2. Lithium disilicate and either β-spodumene or β-quartz are the two predominant crystalline phases (by weight) of the glass-ceramic article. The glass-ceramic article further comprises tetragonal ZrO.sub.2 as a crystalline phase. The composition of the glass-ceramic article from a primary surface into a thickness of the glass-ceramic article can comprise over 10 mol % Na.sub.2O (on an oxide basis), with the mole percentage of Na.sub.2O decreasing from the primary surface towards the center-volume. The glass-ceramic article exhibits a ring-on-ring load-to-failure of at least 120 kgf, when the thickness of the glass-ceramic article is 0.3 mm to 2.0 mm.

Sheet-like glass ceramic article are provided that include surfaces with a thickness between the surfaces between 0.5 mm and 1.9 mm and a core. The articles have a first microstructure provided on each of the surfaces and have a second microstructure in the core with a second thickness (d.sub.2). The first microstructures extend inwardly from the surfaces towards the core and has a first thickness (d.sub.1). The first microstructure has a difference from the second microstructure selected from a group consisting of: a crystalline phase type, a crystalline phase amount, crystalline phase size distribution, crystalline phase orientation, crystalline phases composition, crystalline inclusion, an amorphous phase type, an amorphous phase percentage amount, an amorphous phase composition, and any combinations thereof. The difference results in a first coefficient of linear thermal expansion of the first microstructure that is smaller than a second coefficient of linear thermal expansion of the second microstructure.

The present applicationprovides transparent glass-ceramics of lithium aluminosilicate type, of β-quartz, the composition of which contains a low content of lithium, articles constituted at least in part by said glass-ceramics, precursor glasses for said glass-ceramics, and also a method of preparing said articles. Said glass-ceramics have a composition, expressed in percentages by weight of oxide, containing63% to 67.5% of SiO.sub.2; 18% to 21% of Al.sub.2O.sub.3; 2% to 2.9% of Li.sub.2O; 0 to 1.5% of MgO; 1% to 3.2% of ZnO; 0 to 4% of BaO; 0 to 4% of SrO; 0 to 2% of CaO; 2% to 5% of TiO.sub.2; 0 to 3% of ZrO.sub.2; 0 to 1% of Na.sub.2O; 0 to 1% of K.sub.2O; 0 to 5% of P.sub.2O.sub.5; with (0.74 MgO+0.19 BaO+0.29 SrO+0.53 CaO+0.48 Na.sub.2O+0.32 K.sub.2O)/Li.sub.2O<0.9; optionally up to 2% of at least one fining agent; and optionally up to 2% of at least one coloring agent.

Glass ceramic material for the production of synthetic stones in fashion jewellery and jewellery, having excellent mechanical properties, chemical and heat resistance, harmless due to absence of lead, arsenic and cadmium compounds, available in a broad scale of colour designs, imitating faithfully natural precious stones thanks to high content of spinel crystalline phase and lowered content of SiO.sub.2, consisting of (in weight %):

20-40% SiO.sub.2,
1.5-10% B.sub.2O.sub.3,
20-35% Al.sub.2O.sub.3,
0.1-20% MgO,
0.1-20% ZnO,
the content of MgO+ZnO being at least 10%,
preferably also
0-15% TiO.sub.2,
0.1-15% ZrO.sub.2,
the content of TiO.sub.2+ZrO.sub.2 being at least 5%,
more preferably also
0-20% of colouring additives in the form of CoO, NiO, CuO, Fe.sub.2O.sub.3, MnO.sub.2, Cr.sub.2O.sub.3, V.sub.2O.sub.5, Pr.sub.2O.sub.3, CeO.sub.2, Nd.sub.2O.sub.3, Er.sub.2O.sub.3, AgO and Au.

A transparent 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 including tetragonal ZrO.sub.2. The glass ceramic may be ion exchanged. Methods for producing the glass ceramic are also provided.

A composition includes 30 mol % to 60 mol % SiO.sub.2; 15 mol % to 40 mol % Al.sub.2O.sub.3; 5 mol % to 25 mol % Y.sub.2O.sub.3; 5 mol % to 15 mol % TiO.sub.2; and 0.1 mol % to 15 mol % RO, such that RO is a sum of MgO, CaO, SrO, and BaO.

The present invention provides a microcrystalline glass product. The microcrystalline glass product includes the following components in percentage by weight: SiO.sub.2: 45-70%; Al.sub.2O.sub.3: 8-18%; Li.sub.2O: 10-25%; ZrO.sub.2: 5-15%; P.sub.2O.sub.5: 2-10%; and Y.sub.2O.sub.3: greater than 0 but less than or equal to 8%. Through reasonable component design, the microcrystalline glass and the microcrystalline glass product obtained in the present invention have excellent mechanical and optical properties and are suitable for electronic devices or display devices.