Effect of water on sodium ion mobility in sodium magnesium aluminosilicate glasses by internal friction analysis

• Internal friction for SiO2–Al2O3–Na2O–MgO glasses containing water was measured.
• Low temperature friction peak due to alkali ion motion changes with increasing water.
• Low temperature relaxation changes by the presence of proton and aluminum ions.

The effect of water on the internal friction of SiO2–Al2O3–Na2O–MgO glasses with water content up to 0.070 mol/l was determined. For (74 − x)SiO2–xAl2O3–(26 − y)Na2O–yMgO glasses in which 0 ≦ x ≦ 3 and 0 ≦ y ≦ 16, the low temperature friction peak below 200 °C caused by the stress-induced movement of sodium ion shifts to higher temperature, and its activation energy becomes larger with increasing water content. This result suggests that the low temperature motion of Na+ ion (γ relaxation) becomes slower by addition of water. For 69SiO2–5Al2O3–13Na2O–13MgO glass, however, adding water enhanced sodium ion movement since aluminate tetrahedral became charge balanced by H+ instead of Na+ cation, thereby inducing γ relaxation.