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Line Profile Analyses of Rhodium Metal Obtained by Decomposition of Rhodium Carbonyl

Published online by Cambridge University Press:  06 March 2019

Dhanesh Chandra ,
Himanshu Mandalia ,
Michael L. Garner ,
Mary Kay Blakely  and
K. H. Lau
Dhanesh Chandra
Affiliation:
Department of Chemical and Metallurgical Engineering, Mail Stop 170 Mackay School of Mines University of Nevada, Reno NV 89557
Himanshu Mandalia
Affiliation:
Department of Chemical and Metallurgical Engineering, Mail Stop 170 Mackay School of Mines University of Nevada, Reno NV 89557
Michael L. Garner
Affiliation:
Department of Chemical and Metallurgical Engineering, Mail Stop 170 Mackay School of Mines University of Nevada, Reno NV 89557
Mary Kay Blakely
Affiliation:
U.S. Bureau of Mines, Reno Research Center 605 Evans Avenue Reno, NV 89512
K. H. Lau
Affiliation:
SRI International 333 Ravenswood Avenue Menlo Park CA 94025
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Abstract

Metal carbonyls are important for chemical vapor deposition (CVD) of metals and alloys and formation of high surface area metallic particles which have potential applications as catalysts. Rhodium carbonyl [Rh6(CO)16] produces high surface area metallic particles whose structure has been reported as monoclinic (I2/a) with lattice dimensions, a=17.00(±0.03)Å, b=9.78(±0.02)Å, c=17.53(±0.03)Å and β=121°45' ± 30' at room temperature. Generally, metal carbonyl crystals dissociate under vacuum as carbonyl gas and decompose to metallic crystals and carbon monoxide at higher temperatures. However, the behavior of rhodium carbonyl crystals is different; they decompose directly to metallic rhodium without the formation of rhodium carbonyl gas in vacuum. Several residual fine grains of rhodium metal are found after the decomposition in vacuum at relatively low temperatures. The metallic samples of rhodium were obtained from vapor pressure experiments using torsion Knudsen-effusion apparatus. X-ray diffraction analyses performed on these grains showed severely broadened Bragg reflections indicative of small particle size and/or lattice microstrain. In this study, a comparison of lattice strains and domain sizes obtained by integral breadth and Fourier methods has been made. In addition a comparison of the lattice strains and domain sizes has been made between the Cauchy, Gaussian, Cauchy-Gaussian and Aqua integral breadth methods.

Type
V. Residual Stress, Crystallite Size and rms Strain Determination by Diffraction Methods
Information
Advances in X-Ray Analysis , Volume 38: Forty-third Annual Conference on Applications of X-ray Analysis , 1994 , pp. 413 - 425
Copyright
Copyright © International Centre for Diffraction Data 1994

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