Self-diffusion of /sup 60/Co in Co/sub 1-x/ O single crystals of controlled stoichiometry

Journal Article · Sat Jan 01 04:00:00 EST 1977 · J. Am. Ceram. Soc.; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1977.tb16097.x· OSTI ID:6067518

Rahman, S F; Berard, M F

Cobalt tracer self-diffusion coefficients were determined in single crystals of Co/sub 1-x/O at 1037 to 1350/sup 0/C and for x = 0.002 to 0.008. In crystals with x fixed at 0.005, the results were D/sub Co/ = 3.89 x 10/sup -4/ exp (-31,600 +- 2400/RT) cm/sup 2//S. The activation energy in this constant-stoichiometry case was identified as the enthalpy of motion for Co ions moving via a vacancy jump mechanism. Based on known stoichiometry relations, a published activation energy for Co self-diffusion measurements in air was corrected to yield an enthalpy of motion in excellent agreement with the number given above. At a constant temperature of 1150/sup 0/ +- 2/sup 0/C, the P/sub O/sub 2// dependence of Co self-diffusion was D/sub Co/ = 9.74 x 10/sup -9/P/sub O/sub 2// /sup 0/ /sup 279/ cm/sup 2//S. The P/sub O/sub 2// exponent suggests that the predominant mobile ion defects are singly ionized Co vacancies. Simple defect reactions with no modifications for defect clustering were adequate to explain all results obtained.

• Research Organization: Ames Lab., IA
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6067518
• Journal Information: J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 60:1-2; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ACTIVATION ENERGY
ATOM TRANSPORT
CHALCOGENIDES
COBALT
COBALT COMPOUNDS
COBALT OXIDES
CRYSTALS
DIFFUSION
ELEMENTS
ENERGY
METALS
MONOCRYSTALS
NEUTRAL-PARTICLE TRANSPORT
OXIDES
OXYGEN COMPOUNDS
RADIATION TRANSPORT
SELF-DIFFUSION
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VERY HIGH TEMPERATURE