Helium migration in alkali germanate glasses
Helium permeability, diffusivity, and solubility have been measured for sodium, potassium, rubidium, and cesium germanate glasses, and for one series of sodium-potassium germanate glasses. In each case, the helium permeability and diffusivity exhibit minima in the property-composition curves. These minima shift to greater alkali oxide content and increase in magnitude in the order Cs, Rb, K, Na-K, Na. These minima result from corresponding maxima in activation energy for helium migration. Helium solubilities do not exhibit similar minima, but rather decrease monotonically with increasing alkali oxide content. These results appear to be related to free-volume changes in the glasses as a function of composition. The inability of the current structural model for these glasses to explain the results of the present study raises questions regarding the validity of that model.
- Research Organization:
- Sandia Laboratories, Livermore, California 94550
- OSTI ID:
- 6479723
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 50:1; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
ACTIVATION ENERGY
ALKALI METAL COMPOUNDS
AMORPHOUS STATE
CESIUM COMPOUNDS
CHEMICAL BONDS
CRYOGENIC FLUIDS
DIFFUSION
ELEMENTS
ENERGY
FLUIDS
GERMANATES
GERMANIUM COMPOUNDS
GLASS
HELIUM
NONMETALS
OXYGEN COMPOUNDS
PERMEABILITY
RARE GASES
RUBIDIUM COMPOUNDS
SODIUM COMPOUNDS
SOLUBILITY