Luka Pavić

Electrical, dielectric and spectroscopic studies on MnO doped LiI–AgI–B2O3 glasses

LiI–AgI–B2O3 glasses doped with different concentrations of MnO (ranging from 0 to 0.8 mol%) were prepared. Electrical and dielectric properties have been studied over a wide frequency range of 10−2 – 106 Hz and in the temperature range from 173 to 523 K. The valence states of manganese ions and their coordination in the glass network have been investigated using optical absorption, luminescence, and ESR spectroscopy. The analysis of the spectroscopic results has indicated that the manganese ions exist in both Mn2+ and Mn3+ states and occupy octahedral and tetrahedral positions. With increasing MnO concentration there is a gradual increase in the tetrahedral occupancy of Mn2+ ions at the expense of octahedral occupancy in the glass network. The results of dc conductivity have indicated that when T > θD/2, the small polaron hopping model is appropriate and the conduction is adiabatic in the nature. Further, the analysis of experimental data indicates that there is a mixed, ionic and electronic, conduction....

Polaronic behavior of MnO doped LiI-AgI-B2O3 glass

The ac electrical conductivity and dielectric constant of LiI-AgI-B2O3 glass doped with 0.1 mol. % MnO were investigated in the frequency range from 1 Hz to 1 MHz and the temperature range from 5 K to 450 K. At temperatures below 450 K, an ac conductivity and dielectric constant follow the universal dielectric response (UDR), being typical for hopping or tunneling of localized charge carriers. A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that, below 450 K, this mechanism governs the charge transport in this glass. The comparison of the values of characteristic coefficients W∞ and Eac determined by two different methods confirms the polaronic behavior of this system.