Isothermal mechanical relaxations in single and mixed alkali silicate glasses.

Laurence Chocinski-Arnault (1) , André Rivière (1)

1 LMPM - Laboratoire Mécanique et Physique des Matériaux

Very low frequency damping measurements carried out in various mixed alkali silicate glasses (1 x)Na2O.xLi2O.3SiO2 with x = 0, 0.25, 0.5 and 0.75 point out new experimental features. A new relaxation peak occurring at very low temperature is evidenced in the single alkali glass (x = 0) in more that the two classical relaxation peaks previously described and assigned respectively to the motion of alkali ions (ionic peak) and to a local rearrangement of the glassy structure involving non-bridging oxygen (NBO peak). For the three mixed alkali glasses, the mixed alkali relaxation peak is shown to be superimposed to two satellite peaks corresponding to the ionic and NBO peaks. In more, Arrhenius plots of the mixed alkali peak are not on one straight line: the apparent activation energy is different below and above 340 K. These experimental results are discussed using recent models proposed for the alkali effect and a model developed previously for mechanical relaxation in ionic glasses below Tg.

Mots clés: Physical Sciences

Domaines: Sciences de l'ingénieur [physics]

Laurence Chocinski-Arnault, André Rivière. Isothermal mechanical relaxations in single and mixed alkali silicate glasses.. Philosophical Magazine, 2007, 87 (3-5), pp.749-757. ⟨10.1080/14786430601021629⟩. ⟨hal-00513788⟩