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Author Masing, L. ♦ Orme, J. E. ♦ Young, L.
Sponsorship USDOE
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Publisher The Electrochemical Society
Language English
Subject Keyword METALS, CERAMICS, AND OTHER MATERIALS ♦ ANODES ♦ FILMS ♦ NIOBIUM ♦ NIOBIUM ALLOYS ♦ OPTICAL PROPERTIES ♦ OXIDES ♦ QUANTITATIVE ANALYSIS ♦ SPECTROMETERS ♦ SULFURIC ACID ♦ TANTALUM ♦ TANTALUM ALLOYS ♦ THICKNESS ♦ ZIRCONIUM
Abstract The reflectivity of anodized electropolished tantalum was measured as a function of angle of incidence for 4358A light polarized in the plane of incidence. The principal aim of these measurements was to obtain the refractive index of the oxide. This is needed to determine absolute thicknesses of oxide by the spectrophotometric method in which the wavelengths of minimum reflectivity due to interference at near normal incidence are determined. The measurements also provided a method of determining the optical constants of the metal, without assuming that the surface is perfectly flat or that an unsnodized surface is free from oxide. It was found that films formed on tantalum in 0.2N H/sub 2/SO/sub 4/ have a thin outer layer of light-absorbing oxide. The bulk of the film is, however, nonabsorbing and homogeneous. A large part of the thickness of films formed in concentrated sulfuric acid absorbs light. The refractive index at 4358A wavelength of films formed in dilute solution increases by about 0.3% per tenfold decrease in the current density at which they are made and by about 0.06% per 10 deg C rise in the temperature at which they are made. The refractive indices of films formed on niobium, on 25 at.% Ta--75 at.% Nb, snd on 25 at.% Nb-- 75 at.% Ta were estimated and a preliminary study was made of films on zirconium.
ISSN 00134651
Educational Use Research
Learning Resource Type Article
Publisher Date 1961-01-01
Publisher Department Univ. of British Columbia, Vancouver
Journal Journal of the Electrochemical Society
Volume Number 108
Issue Number 5
Organization Univ. of British Columbia, Vancouver


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