Glass Peak Research Articles

Electrical Properties and Internal Friction in Iron Phosphate Glasses

The internal friction and electrical properties of glasses in 40Fe2O3⋅60P2O5 system were measured. The quantitative values of dynamic modulus G′ and dynamic loss G″ on internal friction were obtained by considering the shape factor. G′ was 3.0×109-1.0×1010dyn/cm2, and G″ was 1.0×107-5.0×107dyn/cm2 in the range of valence ratio (Re=Fe2+/Fe2++Fe3+)Re=0.13 to Re=0.37. The two peaks were observed in the temperature range from -100° to 400°C at a frequency of about 1Hz. The area of the low temperature peak (at about 0°C) increased with increasing valence ratio Re similar to that in the D. C, conductivity and dielectric increment. All of internal friction peak and electrical properties showed maxima at Re=0.5. Frequency temperature dependence of the dielectric loss peak and low temperature peak on internal friction showed a straight line and its activation energy was 0.55 eV. The internal friction peak in glasses of 40MgO⋅60P2O5 system was not observed in the temperature range -100° to 200°C. From the above results the peak observed at low temperature was due to the hopping of localized electron in small polaron. On the other hand, the activation energy of high temperature peak was about 1.6eV (37kcal/mol) and the high temperature peak decreased with increasing Re ratio, Consequently, the peak observed at high temperature was considered as due to the interaction between proton and non-bridging oxygen ions.

Structure and Properties of Silver Borate Glasses

Clear glasses form in the system Ag2O-B2O3 up to about 35 mol% (65 wt%) Ag2O. Infrared absorption, thermal expansion, and density data indicated an analogy to the Na2O-B2O3 system. Pentaborate-triborate group pairs appear to be formed on addition of Ag2O to B2O3 up to 20 mol% Ag2O and diborate groups from 20 to 33 mol% Ag2O. This interpretation is supported by the comparison of the infrared absorption spectra of quenched and crystallized glasses. One crystallization product, Ag2O-4B2O3, was identified previously. A new compound starts to appear at 28 mol% Ag2O. The theory that silver is generally present as a network modifier like sodium was substantiated by the comparison of the molar volume of sodium and silver borate glasses. Above 27 mol% Ag2O some atomic silver is assumed to be present; below 15 mol%, exploratory studies indicate a two-phase structure within an immiscibility gap. A low-temperature internal friction peak in the glasses up to 28 mol% Ag2O corresponds to the alkali peak in other glasses; a high temperature peak appearing in the 34 mol% Ag2O glass is associated with the appearance of nonbridging oxygen in the system.