Abstract: A high temperature stable composition includes a first material and a second material interspersed within the first material so as to form a structure. The composition is structured such that the first and second materials maintain a periodicity of distribution between about 100 nm and about 1000 nm, and the composition is operable to reflect photons having a wavelength greater than about 700 nm and to emit or transmit photons having a wavelength between about 400 nm and about 700 nm at temperatures greater than about 2000 Kelvin for at least about 10 hours.

Abstract: An apparatus and method for processing materials in supercritical fluids is disclosed. The apparatus includes a capsule configured to contain a supercritical fluid, a high strength enclosure disposed about the capsule and a sensor configured to sense pressure difference between an interior and an exterior of the capsule. The apparatus also includes a pressure control device configured to adjust pressure difference of the capsule in response to the pressure difference sensed by the sensor. The apparatus further includes at least one dividing structure disposed within the capsule that divides the capsule into a seed growing chamber and a nutrient chamber.

Abstract: An organic liquid evaporation system is disclosed. The organic liquid evaporation system comprises a housing having at least one inlet and at least one outlet. At least a first evaporator plate radially extending from a sidewall of the housing, and at least a second evaporator plate radially extending from a sidewall of the housing define a serpentine flow path within the housing. A heating source is in thermal communication with the first evaporator plate and the second evaporator plate, wherein the heating source provides heat to the first and second evaporator plates to evaporate organic liquid introduced within the inlet to produce a vapor through the outlet. A method for preparing powder pre-forms and oxide soot using the organic liquid evaporation system is also disclosed.

Abstract: A crucible for melting a silica for fusion of said silica into a desired shape. The crucible having a main body with inner and outer surfaces comprised of a refractory material. In addition, at least a portion of the inner surface includes a barrier layer comprised of a material selected from rhenium, osmium, iridium, and mixtures thereof. An inlet tube to the crucible being provided to supply an oxidizing gas to a melt zone.

Abstract: A capsule for containing at least one reactant and a supercritical fluid in a substantially air-free environment under high pressure, high temperature processing conditions. The capsule includes a closed end, at least one wall adjoining the closed end and extending from the closed end; and a sealed end adjoining the at least one wall opposite the closed end. The at least one wall, closed end, and sealed end define a chamber therein for containing the reactant and a solvent that becomes a supercritical fluid at high temperatures and high pressures. The capsule is formed from a deformable material and is fluid impermeable and chemically inert with respect to the reactant and the supercritical fluid under processing conditions, which are generally above 5 kbar and 550° C. and, preferably, at pressures between 5 kbar and 80 kbar and temperatures between 550° C. and about 1500° C.

Abstract: A system for sintering a quartz tube, such as a quartz fiber optic sleeve tube. The system comprises a furnace for heating the quartz tube to a temperature of at least 1400° C. in a controlled atmosphere, a support rod assembly for the quartz tube, and means for positioning the quartz tube and a portion of the support rod assembly within the furnace. The support rod assembly includes a cylindrical support rod that straightens and supports the quartz tube and prevents tapering of the inner diameter due to creep, and at least one retaining portion coupled to at least one end of the cylindrical support rod for preventing slippage of the quartz tube from the support rod assembly. A mandrel assembly for fabricating a quartz fiber optic sleeve tube, a method of making a quartz fiber optic sleeve tube using the mandrel assembly, and a quartz fiber optic sleeve tube are also disclosed.

Abstract: A fused quartz article, such as a muffle tube or crucible, with enhanced creep resistance. The enhanced creep resistance is the result of controlled devitrification of the fused quartz article. Controlled devitrification is achieved by coating the article with a colloidal silica slurry doped with metal cations, such as barium, strontium, and calcium. The metal cations in the slurry promote nucleation and growth of cristobalite crystals into the fused quartz at temperatures in the range from about 1000° C. to about 1600° C. The cristobalite has significantly. higher viscosity, and therefore greater creep resistance at elevated temperatures, than fused quartz. Methods for applying a doped coating to a fused quartz article and improving the creep resistance of a fused quartz article are also disclosed.

Abstract: A crucible for melting a silica for fusion of said silica into a desired shape. The crucible having a main body with inner and outer surfaces comprised of a refractory material. In addition, at least a portion of the inner surface includes a barrier layer comprised of a material selected from rhenium, osmium, iridium, and mixtures thereof. An inlet tube to the crucible being provided to supply an oxidizing gas to a melt zone.