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Structure and optical properties of evaporated films of the Cr- and V-group metalsThin films of Cr, Mo, and W rapidly evaporated in high vacuum (5 x 10 to the -7th torr) onto room-temperature substrates show anomalously low reflectance (compared to bulk samples). From electron and X-ray diffraction and electron microscopy, the normal bcc crystal structure is found, but with very fine grains. Columnar grains about 100 A in diameter were separated by a less dense grain-boundary network about 10-A wide. The measured optical conductivity agrees with an inhomogeneous-medium model that assumes the normal crystalline conductivity for the grain interiors, with model parameters that correlate to the observed columnar grain size. In contrast, V and Nb films rapidly evaporated onto room-temperature substrates have the reflectance of bulk crystalline material. On liquid-nitrogen temperature substrates, however, V and Nb have normal bcc crystal structure but with small flat-plate grains, and the same model, with appropriate parameters, accounts for the optical conductivity. The difference between these two groups apparently depends on residual gases segregated at the grain boundaries in the Cr-group films.
Document ID
19800068880
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Nestell, J. E., Jr.
(Dartmouth Coll. Hanover, NH, United States)
Christy, R. W.
(Dartmouth Coll. Hanover, NH, United States)
Cohen, M. H.
(Dartmouth Coll. Hanover, NH, United States)
Ruben, G. C.
(Dartmouth College Hanover, N.H., United States)
Date Acquired
August 10, 2013
Publication Date
January 1, 1980
Publication Information
Publication: Journal of Applied Physics
Volume: 51
Subject Category
Solid-State Physics
Accession Number
80A53050
Distribution Limits
Public
Copyright
Other

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