A compositional range of manganese aluminosilicate glass-ceramics with high durability, and methods for making the same, are described herein. The glass-ceramics can be used in conjunction with electronic devices, such as in protective exteriors for such devices. The glass-ceramics can be characterized as having ring-on-ring strengths of at least 300 MPa and fracture toughnesses of at least 1.5 MPa.Math.m.sup.1/2.

Gradient refractive index (GRIN) materials can include multi-phase composites having substances with differing refractive indices disposed non-uniformly within one another. Particular glass composites having a gradient index of refraction can include: an amorphous phase, and a phase-separated region disposed non-uniformly within the amorphous phase. The glass composites include a mixture containing: GeZ.sub.2 and A.sub.2Z.sub.3 in a combined molar ratio of about 60% to about 95%, and CsX and PbZ in a combined molar ratio of about 5% to about 40%, where A is As, Sb or Ga, X is Cl, Br or I, and Z is S or Se. When A is As, the glass composites include PbZ in a molar ratio of about 15% or less. The amorphous phase and the phase-separated region have refractive indices that differ from one another. More particularly, A is Ga or As, X is Cl, and Z is Se.

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.

A three dimensional glass ceramic article with a thickness between 0.1 mm and 2 mm, having a dimensional precision control of less than or equal to ±0.1 mm. A method for forming a three dimensional glass ceramic article including placing a nucleated glass article into a mold, and heating the nucleated glass article to a crystallization temperature, where the nucleated glass article is in the mold during the heating. Then, holding the nucleated glass article at the crystallization temperature for a duration sufficient to crystallize the nucleated glass article and form a three dimensional glass ceramic article, where the nucleated glass article is in the mold during the holding, and removing the three dimensional glass ceramic article from the mold.

Embodiments of a transparent glass-based material comprising a glass phase and a second phase that is different from and is dispersed in the glass phase are provided. The second phase may comprise a crystalline or a nanocrystalline phase, a fiber, and/or glass particles. In some embodiments, the second phase is crystalline. In one or more embodiments, the glass-based material has a transmittance of at least about 88% over a visible spectrum ranging from about 400 nm to about 700 nm and a fracture toughness of at least about 0.9 MPa.Math.m.sup.1/2, and wherein a surface of the glass-based material, when scratched with a Knoop diamond at a load of at least 5 N to form a scratch having a width w, is free of chips having a size of greater than 3 w.

A transparent β-spodumene glass-ceramic is provided. The glass-ceramic includes a primary crystal phase including a β-spodumene solid solution, a secondary crystal phase including tetragonal ZrO.sub.2, and an amorphous phase. The glass-ceramic may be ion exchanged utilizing molten alkali nitrate salt baths. Methods for producing the glass-ceramic are also provided.

A glass-based article comprising a thickness t; a first clad layer having a first thickness t.sub.C1; a second clad layer having a first thickness t.sub.C2; and a core layer having a first thickness t.sub.o, which core layer is disposed between and bonded to the first and second clad layers. A first compressive stress region extends from a surface of the first clad layer to a first depth of compression DOC.sub.1. A second compressive stress region extends from a surface of the second clad layer to a second depth of compression DOC.sub.2. The first and second compressive stress regions comprise a maximum compressive stress greater than or equal to 500 MPa. A central tension region extends from DOC.sub.1 to DOC.sub.2 and has a maximum central tension CT greater than or equal to 250 MPa. A difference in flaw sizes that produce delayed fracture is less than or equal to 3 μm.

A glass-ceramic article comprises a petalite crystalline phase and a lithium silicate crystalline phase. The weight percentage of each of the petalite crystalline phase and the lithium silicate crystalline phase in the glass-ceramic article are greater than each of the weight percentages of other crystalline phases present in the glass-ceramic article. The glass-ceramic article has a transmittance color coordinate in the CIELAB color space of: L*=from 20 to 90; a*=from −20 to 40; and b*=from −60 to 60 for a CIE illuminant F02 under SCI UVC conditions. In some embodiments, the colorant is selected from the group consisting of TiO.sub.2, Fe.sub.2O.sub.3, NiO, Co.sub.3O.sub.4, MnO.sub.2, Cr.sub.2O.sub.3, CuO, Au, Ag, and V.sub.2O.sub.5.

A heat-resistant synthetic jewelry material having a transparent, semitransparent or nontransparent composite nanocrystalline material on the basis of nanosized oxide and silicate crystalline phases. The material includes at least one of the following crystalline phases: spinel, quartz-like phases, sapphirine, enstatite, petalite-like phase, cordierite, willemite, zirconium, rutile, zirconium titanate, zirconium dioxide with a content of ions of transition elements, rare-earth elements and precious metals of from 0.001 to 4 mol %. One of the crystalline phases is additionally quartz-like solid solutions of lithium magnesium zinc aluminosilicates with a virgilite or keatite structure. The composition is selected from the following components,s SiO.sub.2, Al.sub.2O.sub.3, MgO, ZnO, Li.sub.2O, PbO, ZrO.sub.2, TiO.sub.2, NiO, CoO, CuO, Cr.sub.2O.sub.3, Bi.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2, CeO.sub.2, Nd.sub.2O.sub.3, Er.sub.2O.sub.3, Pr.sub.2O.sub.3 and Au.

A material, especially a glassy material of pyrophosphate type, corresponding to the general formula (I): {[(M.sup.2+).sub.1−x(R.sup.+).sub.2x].sub.2[(P.sub.2O.sub.7.sup.4−).sub.1−y(PO.sub.4.sup.3−).sub.4y/3]} n(H.sub.2O) in which x and y are positive rational numbers each between 0 and 0.8, and n is such that the weight percentage of water in the material is greater than 0 and less than or equal to 95. M.sup.2+ represents a bivalent ion of a metal chosen from calcium, magnesium, strontium, copper, zinc, cobalt, manganese and nickel, or any mixture of such bivalent ions. R.sup.+ represents a monovalent ion of a metal selected from potassium, lithium, sodium, and silver, or any mixture of such monovalent ions. This material in particular can be used in manufacturing of bone replacements or prosthesis coatings.