Ohara, Inc.

Kiyoyuki Momono

Naoyuki Goto

Toshitaka Yagi

Susumu Uehara

Katsuhiko Yamaguchi

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 SiOcomponent of 30.0% or more and 70.0% or less, an AlOcomponent of 8.0% or more and 25.0%, an NaO 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 TiOcomponent of 0% or more and 10.0% or less, the molar ratio [AlO/(MgO+ZnO)] having a value of 0.5 or more and 2.0 or less, and comprising one or more selected from RAlO, RTiO, RTiO, RSiO, RAlSiOand RAlSiOas a crystal phase.

Crystallized glass and crystallized glass substrate

It is an object of the present invention to provide a crystallized glass which has various properties required for employing the substrate for information recording medium of the next generation, and also has significantly low specific gravity; and a crystallized glass substrate for information recording medium. A crystallized glass containing, as a crystal phase, one or more selected from RAlOand RTiO(wherein R is one or more selected from Mg and Fe), the crystallized glass comprising the components of SiOof 50% to 70%, AlOof 10% to 26%, TiOof 1 to 15%, MgO of 2.5% to 25%, FeO of 0% to 8%, and ZnO of 0% to less than 2%, expressed in terms of mass percentage on an oxide basis, wherein the value of (AlO+MgO)/SiOis 0.30 or more and 0.65 or less, and a specific gravity is less than 2.63.

Crystallized glass and crystallized glass substrate for information recording medium

Provided is an optical glass having optical constants, a refractive index (n) of more than 1.9 and an Abbe number (&#x3bd;d) of not more than 38, having a small partial dispersion ratio and capable of being produced from inexpensive materials. The optical glass has a partial dispersion ratio (&#x3b8;g, F) of at most 0.615, and contains, as indispensable ingredients, BO, LaO, TiO, NbOand TaO, wherein the ratio, as % by mass, of TiO/NbOis at most 0.26 and GeO/NbOis at most 0.38. The optical glass contains, in terms of % by mass, the following ingredients: and 

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Sagamihara, Japan

Kiyoyuki Momono