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 00:00:00 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., Ames, IA (United States)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6516086
• Report Number(s): IS-T-818; TRN: 79-005417
• Resource Relation: Other Information: Thesis
• Country of Publication: United States
• Language: English

Related Subjects

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