Actions for Self-diffusion of Co60 in crystals of Co(1-x)O.

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Self-diffusion of Co60 in crystals of Co(1-x)O.

Author
Rahman, Syed Fakhrur
Published
United States : [publisher not identified], 1976.
[Oak Ridge, Tennessee] : [U.S. Atomic Energy Commission], 1976.
Physical Description
microfiche : negative ; 11 x 15 cm

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Summary
Tracer self-diffusion coefficients were measured as functions of temperature and deviations from stoichiometry. The arc-transfer technique of crystal growth was found to produce crystal of Co1-xO of essentially the same purity as the starting Co rod, and the quality was comparable to commercially available crystals grown by Verneuil process. Measurements at x = 0.005 in Co1-xO showed the Co tracer self-diffusion coefficient to be D = 3.88 x 10-4 exp (-31600 ± 2400/RT) cm2/s between 1037 and 1350°C. This activation energy is in agreement with measurements made in air, if proper compensation is made for the effect of variation in stoichiometry. Measurements on crystals having deviations between 0.002 and 0.008 at 1150°C showed the diffusion coefficient to depend on pO2 as D = 9.74 x 10-9 p/sub O2//sup 1/(3.59)/ cm2/s, where p/sub O2/ varied between 10-2.5 and 10-0.25 atm. Comparison with thermogravimetric and electrical conductivity measurements confirms that the defects responsible for Co diffusion in the range of temperature and p/sub O2 of this investigation are singly ionized cobalt vacancies. The Co tracer self-diffusion coefficients in single crystals are nearly identical to those in polycrystalline Co1-xO.
Report Numbers
IS-T-691
Other Subject(s)
Collection
U.S. Atomic Energy Commission depository collection.
Note
DOE contract number: W-7405-ENG-82
NSA number: NSA-33-026402
OSTI Identifier 4013507
Research organization: Ames Lab., Ames, IA (United States).
Funding Information
Sponsored by US Energy Research and Development Administration (ERDA).
View MARC record | catkey: 45376963