Disclosed herein is a dual density disc comprising a dense outer tube comprising a metal oxide having a purity of greater than 92%; and a porous core comprising a metal oxide of a lower density than a density of the dense outer tube; wherein the porous core has a metal oxide purity of greater than 99%; where the dense outer tube has an inner tapered surface.

A member for optical glass production apparatus is a member exposed to a gas containing a halogen element in a high temperature environment; the member includes a first member (4) directly or indirectly supporting an optical glass (10) and a second member (5) supporting the first member (4).

The invention relates to a blank of a ceramic material, wherein a first ceramic material and then a second ceramic material of different compositions are filled into a die and wherein the materials are pressed and after pressing are sintered. A layer of the first ceramic material is thereby filled into the die and a first cavity formed in the layer, the second ceramic material is then filled into the first open cavity and the materials pressed together and then heat-treated.

An yttrium oxide-based sintered body contains yttrium oxide as a main constituent and 0.1 wt % or more and 5.0 wt % or less of zirconium on a ZrO.sub.2 basis. Such an yttrium oxide-based sintered body made with yttrium oxide and a certain amount of zirconium oxide therein is highly resistant to corrosive chemicals while maintaining superior resistance to plasma and corrosive gases.

A refractory object may include a zircon body that may include at least about 0.1 wt. % and not greater than about 5.5 wt. % of an Al.sub.2O.sub.3 containing component for a total weight of the zircon body. The zircon body may further include at least about 25 wt. % and not greater than about 35 wt. % of a SiO.sub.2 component for a total weight of the zircon body.

The invention concerns the area of ceramics an relates to a method for separating impurities from silicon carbide, said method being applicable to SiC powders from grinding sludges, and to temperature-treated and purified silicon carbide powder. The aim of the invention is to provide a method with which different impurities are substantially completely removed using a simple and economical process. This is achieved by a method in which pulverulent SiC waste products that have a mass percent of SiC of at least 50% and an average grain size d.sub.50 ranging from 0.5 to 1000 μm and have been subjected to a temperature treatment and cooled are mechanically treated and physically separated. The physically separated SiC powder is then divided into two fractions, one of which has a mass of impurities that is greater than the mass of impurities in the other fraction at least by a factor of 2.

A light emitting device (1) is a light emitting device for use in a photodynamic therapy. The light emitting device includes: a solid-state light-emitting element (2) that emits primary light in which an energy density is 0.5 W/mm.sup.2 or more; and a wavelength converter (3) including a first phosphor (4) that emits first wavelength-converted light (7). The first wavelength-converted light has a light component across at least a whole of a wavelength range of 700 nm or more and less than 800 nm. Energy of fluorescence emitted from the wavelength converter is 100 mW or more. A medical device includes the light emitting device.

The present invention relates to inorganic fibres having a composition comprising: 61.0 to 70.8 wt % SiO.sub.2; 28.0 to 39.0 wt % CaO; 0.10 to 0.85 wt % MgO other components, if any, providing the balance up to 100 wt %,

The sum of SiO.sub.2 and CaO is greater than or equal to 98.8 wt % and the other components comprise less than 0.70 wt % Al.sub.2O.sub.3, if any.

The present invention relates to a laminated member including: a glass member having a linear transmittance at a wavelength of 850 nm of 80% or more; a bonding layer including a resin and lying on the glass member; and a Si—SiC member lying on the bonding member, in which the Si—SiC member has an average linear expansion coefficient α at from 20° C. to 200° C. of from 2.85 ppm/° C. to 4.00 ppm/° C.

Provided is a sintered body that has high heat dissipation and from which light can be emitted when excited by an excitation light source, a light emitting device, a wavelength conversion member, and a method for manufacturing the sintered body.

The sintered body includes aluminum nitride and europium, has a thermal diffusivity of 27.0 mm.sup.2/s or greater as measured by a laser flash method at 25° C., and emits green light when excited by an excitation light source.