Abstract:
High temperature superconducting oxide materials can be taken to a higher, but stable, state of oxidation by removing H-impurities, such as OH , using I2/O2 mixtures in a reactive atmosphere process. A higher Tc and a narrower DELTA T-transition result.
Abstract:
A process for depositing diamond (12) onto a substrate (14), which is of particular utility in fabricating very thin layers of diamond. Diamond (12) is deposited by chemical vapor deposition of a hydrocarbon vapor wherein the carbon atoms are saturated and the ratio of hydrogen atoms linked to carbon atoms is less than 2. That is, the carbon atoms of the hydrocarbon are bonded by single bonds at an angle near 109.5 degrees, the same angle required for the carbon atoms in the deposited diamond. The limited number of hydrogen atoms ensures a compact structure for the hydrocarbon, and reduces the system burden of removing excess hydrogen upon deposition. The polycyclic alkanes exhibit the required structures. Preferred hydrocarbons include adamantane (Fig. 2), congressane (Fig. 3), cubane (Fig. 4), and basketane (Fig. 5).
Abstract:
A method for producing an optical fiber preform (10) having a core portion of reduced HO impurity content, wherein a doped silica core layer (12) is deposited onto the inner surface of a tube formed of fused silica in the presence of a reactive gas mixture of iodine and oxygen, the doped silica core layer (12) being formed by oxidizing chlorides of silicon and dopant elements to their respective oxides and then collapsing the tube (11) to form the preform (10).
Abstract:
A process for the removal of water and water derived impurities, e.g. OH-, substitutionally or interstitially incorporated in the structure of crystalline and amorphous materials, e.g. fused silica or aluminum oxide, wherein the material is exposed in powdered form to a gaseous mixture of halogen and carbon monoxide at a predetermined elevated temperature. The mixture of halogen and carbon monoxide reacts to cause the water and OH- ion concentration in the processed material to be reduced to an extremely low level. Materials purified by the process can be used to produce optical fibers and laser windows of excellent mechanical, thermal and optical properties.
Abstract:
A catalyst material having a catalyst metal selected from the group consisting of platinum, iridium, rhodium and palladium, supported on a substrate, selected from the group consisting of aluminum oxide and tin oxide, wherein the substrate has at least two types of surface atomic sites at which the catalyst metal can reside, and the catalyst metal resides primarily in one of those types of sites. In one catalyst material having platinum supported on an aluminum oxide substrate, the platinum atoms are located predominantly in the substrate sites having the lowest activation energy for catalysis of a chemical reaction. Population of only the low energy type of site is achieved by limiting the platinum content to from about 0.25 to about 1.0 atomic percent.
Abstract:
Method for the preparation of ultrapure active metal fluorides of increased purity from their metal oxides by reacting an active metal with a predetermined amount of HF(aq) to form a solid reaction product which is dried under controlled heating to form a hydrated fluoride. This hydrated active metal fluoride is then subjected to reactive atmosphere processing comprising hydrofluoric acid vapor in a CO2 reactive carrier gas and a selected halide compound in the gas phase for a predetermined period of time to further increase anion purity.
Abstract:
Method for the preparation of ultrapure active metal fluorides of increased purity from their metal oxides by reacting an active metal with a predetermined amount of HF(aq) to form a solid reaction product which is dried under controlled heating to form a hydrated fluoride. This hydrated active metal fluoride is then subjected to reactive atmosphere processing comprising hydrofluoric acid vapor in a CO2 reactive carrier gas and a selected fluoride compound in the gas phase for a predetermined period of time to further increase anion purity.