Search Results

Advanced search parameters have been applied.
open access

Exploring novel silicon-containing polymers---From preceramic polymers to conducting polymers with nonlinear optical properties

Description: Several new types of silicon-containing preceramic polymers, i.e., poly(diorganosilacetylene) and poly(diorganosilvinylene) have been synthesized with molecular weights from 10,000 to 120,000. These polymers could be thermally converted to SiC with a moderate to high char yields. Ready solubility and good processability made these types of polymers attractive in their applications to ceramics. The thermal polymerization of diethynyldiphenyl-silane, which was reported in 1968 to afford poly(diph… more
Date: October 7, 1991
Creator: Pang, Yi.
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we described a particle-in-binder approach to immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fi… more
Date: May 1, 2006
Creator: Baker, Gregory L.; Ghosh, Ruby N.; III, D.J. Osborn & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Synthesis, characterization, and reactivity of sulfided hexanuclear molybdenum cluster compounds

Description: Hexanuclear molybdenum clusters with mixed chloride and sulfide bridging ligands were prepared by reacting {alpha}-MoCl{sub 2} with sodium hydrosulfide in the presence of sodium butoxide. The resulting species, Mo{sub 6}Cl{sub (8-x)}S{sub x}{center dot}npy(x {congruent} 3.6, n {congruent} 4, py = pyridine), was pyrophoric and insoluble. The mixed sulfide chloride cluster species Mo{sub 6}S{sub 4}Cl{sub 4}{center dot}6OPEt{sub 3} and Mo{sub 6}S{sub {approximately}5}Cl{sub {approximately}3}{cente… more
Date: September 21, 1990
Creator: Spink, D.
Partner: UNT Libraries Government Documents Department
open access

Synthesis of two mercaptide-substituted hexanuclear molybdenum halide clusters. [((Mo/sub 6/Cl/sub 8/)(SCH/sub 2/CH/sub 3/)/sub 4/(C/sub 5/H/sub 5/N)/sub 2/) and Na/sub 2/((Mo/sub 6/Cl/sub 8/)(SCH/sub 2/CH/sub 3/)/sub 6/) x 3(C/sub 5/H/sub 5/N)]

Description: Two new derivatives of the ((Mo/sub 6/Cl/sub 8/)Cl/sub 4/) cluster have been prepared. Na/sub 2/((Mo/sub 6/Cl/sub 8/)(SC/sub 2/H/sub 5/)/sub 6/) . 3(C/sub 5/H/sub 5/N) was made by first reacting molybdenum dichloride with sodium ethyl mercaptide (1:6 mole ratio) in refluxing methanol. The orange product was recovered in pure crystalline form by extraction of the solid residue with pyridine. This compound was characterized by its X-ray powder pattern, elemental analysis, and infrared and electro… more
Date: March 1, 1977
Creator: Michel, J. B.
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. Due to the improved mechanical pro… more
Date: September 30, 2006
Creator: Baker, Gregory L.; Ghosh, Ruby N.; Osborn, D. J. & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: Spectroscopy of Mo{sub 6}Cl{sub 12} immobilized in a sol-gel matrix and heated to 200 C has been performed. Oxygen quenching of the luminescence was observed. Aging Mo{sub 6}Cl{sub 12} to temperatures above 250 C converts the canary yellow Mo{sub 6}Cl{sub 12} to a non-luminescent gray solid. Preliminary experiments point to oxidation of the clusters as the likely cause of thermally induced changes in the physical and optical properties of the clusters.
Date: September 30, 2003
Creator: Baker, Gregory L.; Ghosh, Ruby N. & Osborn, D. J.
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications has been developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. We report on a fiber optic technique for detection of gas phase oxygen up to 100 C based on the {sup 3}O{sub 2} quenching of the luminescence from molybdenum chloride clusters, K{sub 2}Mo{sub 6}Cl{sub 14}. The inorganic sensing film is a composite … more
Date: September 30, 2006
Creator: Baker, Gregory L.; Ghosh, Ruby N.; Osborn, D. J. & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. This particle-in-binder approach a… more
Date: June 30, 2006
Creator: Baker, Gregory L.; Ghosh, Ruby N.; Osborn, D.J. & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Synthesis and structure of two octahedral molybdenum chloride sulfide clusters

Description: A preparation for chloride sulfide Mo/sub 6/X/sub 8/ clusters has been devised which employs substitution by sulfide into the Mo/sub 6/Cl/sub 8//sup 4 +/ cluster. The Mo/sub 6/Cl/sub 7/S/sup 3 +/ cluster has been isolated in the two compounds (C/sub 5/H/sub 5/NH)/sub 3/((Mo/sub 6/Cl/sub 7/S)Cl/sub 6/) x 3(C/sub 5/H/sub 5/NH)Cl and (C/sub 5/H/sub 5/NH)/sub 3/((Mo/sub 6/Cl/sub 7/S)Cl/sub 6/). The structures of both compounds were determined by single crystal x-ray techniques. Despite the differen… more
Date: March 1, 1980
Creator: Michel, John Byrne
Partner: UNT Libraries Government Documents Department
open access

Vapor Deposition of Molybdenum and Niobium Coatings on Stainless Steel Tubes

Description: Apparatus was developed for vapor depositing molybdenum on the outside of O.1835-in.-OD by 20-in.-long Type 304 stainless steel tubing by hydrogen reduction of molybdenum pentachloride or by thermal decomposition of molybdenum hexacarbonyl, both processes being carried out at reduced pressure. The coatings obtained were uniform, but quite brittle. Apparatus also was developed for vapor depositing niobium on the inside of the abovementioned tubing by hydrogen reduction of niobium pentachloride a… more
Date: October 1, 1957
Creator: Powell, C. F.; Rosenbaum, D. M.; Palmer, R. B. & Campbell, I. E.
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Alkali salts of Mo{sub 6}Cl{sub 12} were synthesized and heated to 280 C for one hour in air. Optical measurements of the thermally treated material confirm the potential of the salts as lumophores in high temperature fiber optic sensors. In additi… more
Date: July 1, 2004
Creator: Baker, Gregory L.; Ghosh, Ruby N. & III, D.J. Osborn
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: A reflection mode fiber optic oxygen sensor is being developed that can operate at high temperatures for power plant applications. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Two critical materials issues are the cluster's ability to withstand high temperatures when immobilized in a porous the sol-gel support, and whether after heating to high temperatures, the sol-gel matrix maintains a high and constant permeability t… more
Date: July 1, 2005
Creator: Baker, Gregory L.; Ghosh, Ruby N.; III, D.J. Osborn & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. One of the critical materials issues is to demonstrate that the luminescent cluster immobilized in the sol-gel porous support can withstand high temperature. At the same time the sol-gel matrix must have a high permeability to oxygen. Using a potas… more
Date: April 1, 2005
Creator: Baker, Gregory L.; Ghosh, Ruby N.; III, D.J. Osborn & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. High temperature measurements of the emission of clusters in sol gel films show that the luminescence intensity from the films follow a 1/T relationship from room temperature to 150 C, and then declines at a slower rate at higher temperatures. The … more
Date: October 1, 2004
Creator: Baker, Gregory L.; Ghosh, Ruby N. & III, D.J. Osborn
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we immobilized the potassium salt of a molybdenum cluster, K{sub 2}M{sub 6}Cl{sub 14}, in a sol-gel matrix and showed that the luminescence is stable after 54 hours at 200 C, but the quenching ratios were low and the films delaminated af… more
Date: October 1, 2005
Creator: Baker, Gregory L.; Ghosh, Ruby N.; III, D.J. Osborn & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. One of the critical materials issues is to demonstrate that the luminescent cluster immobilized in the sol-gel porous support can withstand high temperature. At the same time the sol-gel matrix must have a high permeability to oxygen. Using a potas… more
Date: January 1, 2005
Creator: Baker, Gregory L.; Ghosh, Ruby N.; III, D.J. Osborn & Zhang, Po
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: In this report, initial results pertaining to the synthesis molybdenum clusters and characterization using absorption, optical microscopy, and x-ray powder diffraction are discussed. The synthesis was performed according to literature [1], but results from x-ray powder diffraction indicate that the synthesis did not give the desired compound. The absorption and optical microscopy indicate that the compound synthesized has properties similar to the desired Mo{sub 6}Cl{sub 12} clusters [2,3], so … more
Date: January 1, 2003
Creator: Baker, Gregory L.; Ghosh, Ruby N. & III, D.J. Osborn
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: Mo{sub 6}Cl{sub 12}, a cluster compound whose luminescence depends on the ambient concentration of oxygen, is the basis for a real-time oxygen sensor for combustion applications. Previously, the properties of Mo{sub 6}Cl{sub 12} have largely been studied at room temperature; these studies have now been extended to 200 C. Optical microscopy shows that Mo{sub 6}Cl{sub 12} undergoes a steady change in color as it is heated from room temperature to 200 C, changing from canary yellow to crimson and … more
Date: July 1, 2003
Creator: Baker, Gregory L.; Ghosh, Ruby N. & III, D.J. Osborn
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. The luminescence of Mo{sub 6}Cl{sub 12} immobilized in a sol-gel matrix was measured as a function of heater temperature up to 200 C, in an inert environment. While the luminescence decreased with temperature, the integrated intensity at 200 C shou… more
Date: April 1, 2004
Creator: Baker, Gregory L.; Ghosh, Ruby N. & III, D.J. Osborn
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants Progress Report

Description: More Mo{sub 6}Cl{sub 12} has been synthesized. We have found that previous ambiguous x-ray powder diffraction results are due to disruption of long-range order in the crystals during the heating stage of the synthesis. The quartz cell heaters have been redesigned and are able to heat the substrate. Initial films have been fabricated and are currently under investigation to determine optimal deposition conditions.
Date: May 1, 2003
Creator: Baker, Gregory L.; Ghosh, Ruby N. & III, D.J. Osborn
Partner: UNT Libraries Government Documents Department
open access

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we described a particle-in-binder approach to immobilizing the potassium salt of a molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fibe… more
Date: January 1, 2006
Creator: Baker, Gregory L.; Ghosh, Ruby N.; III, D.J. Osborn & Zhang, Po
Partner: UNT Libraries Government Documents Department
Back to Top of Screen