Kabushiki Kaisha Ohara

Hiroyuki Minamikawa

Naoyuki Goto

Kazuo Ohara

There are provided glass-ceramics comprising, in mass %, 50-60% SiO, 22-26% AlOand 3-5% LiO, having an average crystal grain diameter exceeding 100 nm, and having an average linear thermal expansion coefficient of 30&#xd7;10/&#xb0; C. or below within a temperature range of 0&#xb0; C. to 50&#xb0; C. These glass-ceramics are manufactured by a step of melting glass raw materials, a step of forming the molten glass, a step of annealing the formed glass, a first heat treating step for heat treating the annealed glass at a temperature of 650-750&#xb0; C. for 0.1 hour to 200 hours, and a second heat treating step for heat treating the glass at a temperature of 800-1000&#xb0; C. for 0.1 hour to 50 hours.

Glass-ceramics and method for manufacturing the same

There are provided low expansion transparent glass-ceramics obtained by heat treating a base glass produced at a relatively low melting temperature of 1530&#xb0; C. or below. The glass-ceramics have an average linear thermal expansion coefficient within a range from +6&#xd7;10/&#xb0; C. to +35&#xd7;10/&#xb0; C., 80% transmittance wavelength (T) of 700 nm or below, internal transmittance of 75% or over at light wavelength of 1550 nm, heat resisting temperature of 800&#xb0; C. or over and Young's modulus of 90 GPa or over. The glass-ceramics comprise SiO, AlO, MgO, CaO, BaO, ZnO, LiO, TiOand ZrOand contain &#x3b2;-quartz or &#x3b2;-quartz solid solution as a predominant crystal phase. There are also provided optical waveguide elements and an arrayed waveguide grating (AWG) type planar lightwave circuit utilizing these glass-ceramics.

Low expansion transparent glass-ceramics, glass-ceramic substrate and optical waveguide element

There are provided low expansion transparent glass-ceramics obtained by heat treating a base glass produced at a relatively low melting temperature of 1530&#xb0; C. or below. The glass-ceramics have an average linear thermal expansion coefficient within a range from +6&#xd7;10/&#xb0; C. to +35&#xd7;10/&#xb0; C., 80% transmittance wavelength (T) of 700 nm or below internal transmittance of 75% or over at light wavelength of 1550 nm, heat resisting temperature of 800&#xb0; C. or over and Young's modulus of 90 GPa or over. The glass-ceramics comprise SiO, AlO, MgO, CaO, BaO, ZnO, LiO, TiOand ZrOand contain &#x3b2;-quartz or &#x3b2;-quartz solid solution as a predominant crystal phase.

Low expansion transparent glass ceramics

An aluminosilicate transparent glass has corrosion resistance in the form of mass loss of 4.0 mg or below per 1cm of the surface of a specimen upon holding the specimen for five hours in sodium hydroxide solution having concentration of 300 mg(L under test pressure of 50 MPa at 250&deg; C. The glass has a coefficient of thermal expansion within a range from 35&times;10 /&deg; C. to 50&times;10 /&deg; C. within a temperature range from 100&deg; C to 300&deg; C. The glass has also powdered glass mass loss rate of 0.1% or below in terms of water resistance, acid resistance and alkali resistance.

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Sagamihara, Japan

Hiroyuki Minamikawa