Luminescent Oxide Gels

Newsham, Mark D.; Cerreta, Michael K.; Berglund, Kris A.; Nocera, Daniel G.

doi:10.1557/proc-121-627

Cited by 15 publications

(10 citation statements)

References 4 publications

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“…The sensor tip contains K 2 Mo 6 Cl 14 sol-gel particles embedded in an OtMOS / TEOS binder, with roughly 8 x 10 18 clusters/cm 3 , after accounting for the volume contraction in forming the monolith and drying of the particle/binder composite. The data at 42, 73 and 102 °C are in good agreement with theory.…”

Section: Executive Summarymentioning

confidence: 99%

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Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

et al. 2006

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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 3 O 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 2 Mo 6 Cl 14 , at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fibers with greatly improved mechanical properties. The response of the sensor to oxygen at 40, 70 and 100 °C was measured in 2 -21 % gas phase oxygen. The normalized sensor signal is linear with molar oxygen concentration and fits the theoretical Stern-Volmer relationship. Although the sensitivity decreases with temperature, at 100 °C the sensitivity is 160 [O 2 ] -1 . These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.3

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Section: Executive Summarymentioning

confidence: 99%

“…The sensing film was cured for 16 hours at 70°C. The tip contains roughly 8 x 10 18 clusters/cm 3 , after accounting for the volume contraction in forming the monolith and drying of the particle/binder composite. Fiber Sensor 121 at 42 °C…”

Section: Oxygen Sensitivity Of Fiber Sensors At Elevated Temperaturesmentioning

confidence: 99%

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

et al. 2006

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“…Mussell, Newsham, and Ruud previously reported preliminary studies of the synthesis and optical properties of Mo 6 Cl 12 -based clusters relevant to this project. [1][2][3][4] Mussell described the synthesis of the molybdenum clusters, and Newsham gives a good account of the properties of neutral Mo 6 Cl 12 clusters and their salts, in both solution and a sol gel matrix. Newsham's data indicate that the photophysical properties of the clusters are maintained in sol gel matrices.…”

Section: Introductionmentioning

confidence: 99%

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

et al. 2005

View full text Add to dashboard Cite

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 3 O 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 to oxygen to support rapid quenching of luminescence. We used a composite materials approach to prepare stable sensing layers on optical fibers. We dispersed 60 w/w% of a pre-cured sol-gel composite containing the potassium salt of molybdenum clusters (K 2 Mo 6 Cl 14 ) into a sol-gel binder solution, and established the conditions necessary for deposition of sol-gel films on optical fibers and planar substrates. The fiber sensor has an output signal of 5 nW when pumped with an inexpensive commercial 365 nm ultraviolet light emitting diode (LED). Quenching of the sensor signal by oxygen was observed up to a gas temperature of 175 °C with no degradation of the oxygen permeability of the composite after high temperature cycling. On planar substrates the cluster containing composite responds within <1 second to a gas exchange from nitrogen to oxygen, indicating the feasibility of real-time oxygen detection. (10×) showing a sol-gel monolith containing MM5 pulverized using a mortar and pestle, 25 -250 µm particle size, (b) a sol-gel monolith (no clusters), 1 -2 µm particle size, and (c) dark field image (100×) showing a sol-gel monolith containing MM5 pulverized via ball milling, 2 -8 µm particle size. 3 20Figure 8 Typical dip coating results for deposition of composite / sol-gel binder blends 1000 µm diameter fibers. Details of the fiber fabrication and resultant measurements are in Table 2. 21Figure 9: Processing schemes used for fibers and planar sample (slide) 38Q. The principal differences between 38Q and the fibers is that (i) the binder used for 38Q contained molybdenum clusters whereas that for the fibers did not and (ii) 38Q was cured at 200 °C whereas the fibers were cured at 70 °C.The same cluster/sol-gel monolith was used for all samples. 22Figure 10: Specifications of the optical fibers used for oxygen fiber sensor fabrication and for testing the mechanical properties of the sol-gel film. Figure 13: High temperature fiber sensor luminescence and oxygen quenching for Fiber D (see Figure 12 for details). Here we demonstrate oxygen quenching of 1.3 ± 0.2 at 175 °C. 28Figure14: Thermal dependence of the emission spectra for film 38Q cured at 200 C for 30 minutes. The emission intensity is a function of temperature, but the line-shape is temperature independent. All spectra were sampled in 99.999% nitrogen environments. The cluster source was MM8 and the film concentration is (5±1.1) × 10 20 clusters/cm 3 based on an estimated film thickness of (700 ± 300) nm. The result demonstration that room temperature quenching ratio...

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“…This requires the ability to sense oxygen levels over a broad range of concentrations with fast response times. Mussell, Newsham, and Ruud previously reported preliminary studies of the synthesis and optical properties of Mo 6 Cl 12 -based clusters relevant to this project [1][2][3][4] . Mussell described the synthesis of the molybdenum clusters, and Newsham gives a good account of the properties of neutral Mo 6 Cl 12 clusters and their salts, in both solution and a sol gel matrix.…”

Section: Introductionmentioning

confidence: 99%

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Baker¹,

Ghosh²,

Osborn³

2004

View full text Add to dashboard Cite

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 3 O 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 large number of photons available at 230 °C is consistent with simple low cost optics for fiber optic probes based on the emission from clusters in sol gel films.3

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Luminescent Oxide Gels

Cited by 15 publications

References 4 publications

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

Fiber Optical Micro-Detectors for Oxygen Sensing in Power Plants

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