Glass-ceramics exhibiting a Vickers indentation crack initiation threshold of at least 15 kgf are disclosed. These glass-ceramics may be ion exchangeable or ion exchanged. The glass-ceramics include a crystalline and amorphous phases generated by subjecting a thin precursor glass article to ceramming cycle having an average cooling rate in the range from about 10 C./minute to about 25 C./minute. In one or more embodiments, the crystalline phase may comprise at least 20 wt % of the glass-ceramics. The glass-ceramics may include -spodumene ss as the predominant crystalline phase and may exhibit an opacity about 85% over the wavelength range of 400-700 nm for an about 0.8 mm thickness and colors an observer angle of 10 and a CIE illuminant F02 determined with specular reflectance included of a* between 3 and +3, b* between 6 and +6, and L* between 88 and 97.

Disclosed herein are glass-ceramic articles including a crystalline phase comprising a jeffbenite crystalline structure. The glass-ceramic articles may include a first surface, a second surface opposite the first surface, and a perimeter defining a shape of the glass-ceramic article. The glass-ceramic articles may further include a phase assemblage comprising one or more crystalline phases and a glass phase. The one or more crystalline phases may include a crystalline phase having the jeffbenite crystalline structure.

An article includes SiO.sub.2 from about 40 mol % to about 80 mol %, Al.sub.2O.sub.3 from about 1 mol % to about 20 mol %, B.sub.2O.sub.3 from about 3 mol % to about 50 mol %, WO.sub.3 plus MoO.sub.3 from about 1 mol % to about 18 mol % and at least one of: (i) Au from about 0.001 mol % to about 0.5 mol %, (ii) Ag from about 0.025 mol % to about 1.5 mol %, and (iii) Cu from about 0.03 mol % to about 1 mol %, and R.sub.2O from about 0 mol % to about 15 mol %. The R.sub.2O is one or more of Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O and Cs.sub.2O. R.sub.2O minus Al.sub.2O.sub.3 ranges from about 12 mol % to about 3.8 mol %.

Provided is a high-strength crystallized glass or substrate having a high visible light transmittance and a good color balance, which is suitable for use in protecting members of portable electronic devices, optical devices and the like. Provided is a crystallized glass comprising, in terms of mol % on an oxide basis: an SiO.sub.2 component of 30.0% or more and 70.0% or less, an Al.sub.2O.sub.3 component of 8.0% or more and 25.0%, an Na.sub.2O component of 0% or more and 25.0% or less, an MgO component of 0% or more and 25.0% or less, a ZnO component of 0% or more and 30.0% or less and a TiO.sub.2 component of 0% or more and 10.0% or less, the molar ratio [Al.sub.2O.sub.3/(MgO+ZnO)] having a value of 0.5 or more and 2.0 or less, and comprising one or more selected from RAl.sub.2O.sub.4, RTi.sub.2O.sub.5, R.sub.2TiO.sub.4, R.sub.2SiO.sub.4, RAl.sub.2Si.sub.2O.sub.8 and R.sub.2Al.sub.4Si.sub.5O.sub.18 as a crystal phase.

A glass ceramic sintered body having a small dielectric loss in a high frequency band of 10 GHz or higher and a wiring substrate using the same are provided. The glass ceramic sintered body contains crystallized glass, an alumina filler, and silica. The content of the crystallized glass is 45 mass % to 85 mass %, the content of the alumina filler is 14.8 mass % to 50.1 mass % in terms of Al.sub.2O.sub.3, and the content of silica is 0.2 mass % to 4.9 mass % in terms of SiO.sub.2.

A glass ceramic sintered body having a small dielectric loss in a high frequency band of 10 GHz or higher and stable characteristics against temperature variation and a wiring substrate using the same are provided. The glass ceramic sintered body contains crystallized glass, an alumina filler, silica, and strontium titanate. The content of the crystallized glass is 50 mass % to 80 mass %, the content of the alumina filler is 15.6 mass % to 31.2 mass % in terms of Al.sub.2O.sub.3, the content of silica is 0.4 mass % to 4.8 mass % in terms of SiO.sub.2, and the content of the strontium titanate is 4 mass % to 14 mass % in terms of SrTiO.sub.3.

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.

Doped, low-temperature co-fired ceramic (LTCC) insulating substrates and related wiring boards and methods of manufacture are disclosed. The doped, LTCC insulating substrate is formed from a baked (e.g., sintered) glass-ceramic aggregate material formed from a glass material, a ceramic filler material, and a composite oxide. The crystallized glass-ceramic aggregate is then doped with Iron and/or Manganese before baking. Iron or Manganese can further reduce dielectric loss and the loss tangent of the LTCC insulating substrate formed from that glass material. The glass material becomes crystallized due to an oxide crystal phase being deposited on the glass material during baking, which reduces the dielectric losses. This may be important for the application use as wiring boards for high radio-frequency (RF) electrical circuits where low dielectric loss and loss tangent is desired to achieve a desired signal transmission delay performance.

Doped, low-temperature co-fired ceramic (LTCC) insulating substrates and related wiring boards and methods of manufacture are disclosed. The doped, LTCC insulating substrate is formed from a baked (e.g., sintered) glass-ceramic aggregate material formed from a glass material, a ceramic filler material, and a composite oxide. The crystallized glass-ceramic aggregate is then doped with Iron and/or Manganese before baking. Iron or Manganese can further reduce dielectric loss and the loss tangent of the LTCC insulating substrate formed from that glass material. The glass material becomes crystallized due to an oxide crystal phase being deposited on the glass material during baking, which reduces the dielectric losses. This may be important for the application use as wiring boards for high radio-frequency (RF) electrical circuits where low dielectric loss and loss tangent is desired to achieve a desired signal transmission delay performance.

Glass-ceramics exhibiting a Vickers indentation crack initiation threshold of at least 15 kgf are disclosed. These glass-ceramics may be ion exchangeable or ion exchanged. The glass-ceramics include a crystalline and amorphous phases generated by subjecting a thin precursor glass article to ceramming cycle having an average cooling rate in the range from about 10 C./minute to about 25 C./minute. In one or more embodiments, the crystalline phase may comprise at least 20 wt % of the glass-ceramics. The glass-ceramics may include -spodumene ss as the predominant crystalline phase and may exhibit an opacity about 85% over the wavelength range of 400-700 nm for an about 0.8 mm thickness and colors an observer angle of 10 and a CIE illuminant F02 determined with specular reflectance included of a* between 3 and +3, b* between 6 and +6, and L* between 88 and 97.