Broadband conductivity spectra of fast-ion-conducting silver selenite glasses: Dependence on power law and scaling

In this letter we have studied broadband conductivity spectra (10 Hz–3 GHz) of fast-ion-conducting silver selenite glasses of compositions x AgI-(1− x )( y Ag 2 O-(1− y )SeO 2 ). We have observed that the conductivity spectra below 10 MHz are characterized by a power law with exponent less than unity, while the conductivity spectra in the high-frequency range (above 10 MHz) have been adequately explained in the framework of the unified site relaxation model with exponent greater than unity. The scaling of the conductivity spectra indicates that the time-temperature superposition principle is valid in the low-frequency regime, but not in the high-frequency regime.