Self-diffusion of Er and Hf inpure and HfO/sub 2/-doped polycrystalline Er/sub 2/O/sub 3/. [Hf-175 and Er-169]

Technical Report · Mon Jan 01 04:00:00 EST 1979

DOI:https://doi.org/10.2172/6516086· OSTI ID:6516086

Scheidecker, R. W.

Using a tracer technique, self-diffusion of Er and Hf was measured over the approximate temperature interval of 1600 to 1970/sup 0/C in pure and HfO/sub 2/-doped polycryatalline Er/sub 2/O/sub 3/. Up to about 10 m/o HfO/sub 2/ dopant level, the Er self-diffusion coefficients followed a relationship based on cation vacancies. Above 10 m/o HfO/sub 2/, deviation from this relationship occurred, apparently due to clustering of cation vacancies and oxygen interstitials around the dopant hafnia ion. The activation energy for the self-diffusion of Er in pure Er/sub 2/O/sub 3/ was 82.2 Kcal/mole and increased with the HfO/sub 2/ dopant level present. Self-diffusion of Hf was measured in pure Er/sub 2/O/sub 3/ having two impurity levels, and a separation of the grain boundary. The volume diffusion of Hf showed both extrinsic and intrinsic behavior with the transition temperature increasing with the impurity level present in Er/sub 2/O/sub 3/. The activation energy for Hf volume diffusion in the intrinsic region was high, i.e. 235 -+ 9.5 Kcal/mole. The grain boundary diffusion was apparently extrinsic over the entire temperature interval Very low Hf self diffusion rates were found in both pure and HfO/sub 2/ doped Er/sub 2/O/sub 3/ compositions. Despite a clustering effect, the HfO/sub 2/ dopant increased the Hf volume diffusion coefficients.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6516086
• Report Number(s): IS-T-818
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ARRHENIUS EQUATION
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DENSITY
DIAGRAMS
DIFFUSION
DOPED MATERIALS
ELEMENTS
ERBIUM
ERBIUM COMPOUNDS
ERBIUM OXIDES
FABRICATION
FRENKEL DEFECTS
GRAIN BOUNDARIES
HAFNIUM
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
INTERSTITIALS
ISOTOPE APPLICATIONS
METALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PERMEABILITY
PHASE DIAGRAMS
PHYSICAL PROPERTIES
POINT DEFECTS
RARE EARTH COMPOUNDS
RARE EARTHS
REFRACTORY METALS
SELF-DIFFUSION
SINTERING
TEMPERATURE DEPENDENCE
TRACER TECHNIQUES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VACANCIES