Diffusion in mixed alkaline alkaline-earth silicate glasses

The diffusion of ⁴⁵Ca (¹³³Ba) in K₂O-2CaO-4SiO₂ (K₂O-2BaO-4SiO₂) glasses was studied using the radiotracer method. The temperature dependence of Ca (Ba) diffusion below the glass transition temperature is accurately described by an Arrhenius equation yielding the activation enthalpy of Ca (Ba) diffusion in K₂O-2CaO-4SiO₂ (K₂O-2BaO-4SiO₂). Dynamic mechanical thermal analyses (DMTA) of the same glasses reveal activation enthalpies of a mobile atom species which are in good agreement with the results of the radiotracer diffusion study. This provides strong evidence that the internal friction peak measured by DMTA is directly associated with the motion of the alkali-earth ions and shows that tracer diffusion measurements are an excellent tool to assign the DMTA-peaks to the underlying mobile atom.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft (SFB 458)

Beteiligte Wissenschaftler:

Dr. H. Bracht, Dipl.-Chem. C. Martiny (Institut für Physikalische Chemie, WWU), Dipl.-Phys. F.V. Natrup, Dr. B. Roling (Institut für Physikalische Chemie, WWU)

Veröffentlichungen:

Natrup, F.V., H. Bracht, C. Martiny, B. Roling: Self-diffusion of alkaline-earth ions in ion-conducting alkali alkaline-earth silicate glasses, Verhandl. DPG (VI) 36, 1/(2001) p. 72