Internal friction and dynamic modulus of metaphosphate glass

Abstract Internal friction and dynamic modulus were measured by a forced torsional vibration method at 0.5–5 Hz in the range of −120 to 300 °C for four kinds of metaphosphate glasses, 50MgO · 50P 2 O 5 (MgP), 48SrO · 52 P 2 O 5 (SrP), 25MgO · 25SrO · 50P 2 O 5 (MgSrP) and 25Na 2 O · 25MgO · 50P 2 O 5 (NaMgP). Three internal friction peaks appeared for MgP at ∼−30, ∼105 and ∼230 °C, and the activation energies of the relaxation behavior obtained from the low, intermediate and high temperature regions were ∼110, ∼250 and ∼580 kJ/mol, respectively. For SrP, those three peaks were also obtained at ∼−45, ∼60 and ∼195 °C, and the activation energies were estimated as ∼95, ∼200 and ∼600 kJ/mol at each temperature, respectively. Two peaks appeared at ∼−50 and ∼160 °C for MgSrP, and ∼−55 and ∼70 °C for NaMgP, respectively. The obtained activation energies were ∼100 and ∼180 kJ/mol for MgSrP, and ∼75 and ∼200 kJ/mol for NaMgP, respectively. It is assumed that the primary peaks (the low temperature region) were influenced by the behavior of Mg 2+ , Sr 2+ and Na 1+ ions, and the secondary peaks (the intermediate temperature region) were based on non-bridging oxygen associated with Mg 2+ , Sr 2+ and Na 1+ ions. Dynamic modulus showed a decreased gradually with increasing temperature in the present temperature range for all the compositions.