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Experimental Determination of Spectral Transmittance of Porous Cerium Dioxide in the Range 900–1700 nm

[+] Author and Article Information
Krithiga Ganesan

Department of Mechanical Engineering,  University of Minnesota, Minneapolis, MN, 55455 e-mail: lipinski@umn.edu

Wojciech Lipiński1

Department of Mechanical Engineering,  University of Minnesota, Minneapolis, MN, 55455 e-mail: lipinski@umn.edu

Approximately 25% and 20% of radiation emitted by blackbodies at 5777 K and 1600 K, respectively, are in the spectral range 900–1,700 nm.

The fitting procedure assumes a guess value for the fit coefficients B1,λ to B4,λ . The fitting functions fλ and gλ are computed and the procedure is repeated until the χ2 objective function reaches a minimum.

1

Corresponding author.

J. Heat Transfer 133(10), 104501 (Aug 15, 2011) (6 pages) doi:10.1115/1.4003970 History: Received January 29, 2011; Revised April 05, 2011; Published August 15, 2011; Online August 15, 2011

Overall transmittance of porous cerium dioxide is measured in the spectral range of 900–1700 nm using dispersive spectroscopy. Dense and porous samples of cerium dioxide with average porosities of 0.08 and 0.72, respectively, are investigated. The transmittance of both sample types increases with decreasing thickness, and this trend is more pronounced for the dense samples. The on-average spectrally increasing transmittance of the dense samples is attributed to the decreasing absorption by bulk cerium dioxide with radiation wavelength. The transmittance of the porous samples, on the other hand, remains approximately constant over the spectrum. Porous samples attenuate radiation stronger than the dense samples at any wavelength in the considered range, and it is hypothesized that this effect is due to more intense scattering. Sharp local variations of the transmittance are observed for both sample types.

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Copyright © 2011 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematic of the experimental setup: (#1) short-arc xenon lamp, (#2) cut-on optical filters, (#3) optical chopper, (#4) monochromator, (#5a) and (#5b) collimating and focusing lens assemblies, (#6) sample holder, (#7a) and (#7b) iris diaphragms, (#8) pinhole, (#9) germanium detector, (#10) lock-in amplifier and chopper head driver, and (#11) PC data acquisition and hardware controlling system

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Figure 2

Dense cerium dioxide samples: (a) Photograph of three selected samples of L = 0.76 mm, 1.22 mm, and 2.03 mm; (b): SEM image with different magnification factors

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Figure 3

Porous cerium dioxide samples: (a) Photograph of three selected samples of L = 0.71 mm, 1.02 mm, and 1.47 mm; (b): SEM images with different magnification factors

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Figure 4

Transmittance of dense cerium dioxide samples as a function of radiation wavelength and for selected values of the sample thickness

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Figure 5

Transmittance of porous cerium dioxide samples as a function of radiation wavelength and for selected values of the sample thickness

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Figure 6

Transmittance of dense samples as a function of sample thickness at (a) λ = 1000 nm and (b) λ = 1500 nm

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Figure 7

Transmittance of porous samples as a function of sample thickness at (a) λ = 1000 nm and (b) λ = 1500 nm

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