Structural, physical, and electrical properties of boro-vanadate-iron glasses doped with K_2O alkali


Abstract: The structural, physical, and electrical properties of semiconducting oxide glasses with composition xK_2O: (95-X) [B_2O_3: 2V_2O_5]: 5Fe_2O_3 (0 \le x \le 30) have been studied. The glasses were prepared by splat-quenching method. Fourier transform infrared spectroscopy (FTIR) studies of these glasses were carried out to study the effect of the modifier and glass former in the glasses. These changes in the molecular structure, bond length, and vibrational group were studied in the spectral range of 400-1350 cm^{-1}. The increase in the intensity and shifting of vibrational bands occurred towards lower wave numbers at 1400-1350 cm^{-1}, 1200 cm^{-1}, and 100-940 cm^{-1}. These structural changes were compared with the electrical conductivity data to see a more clear effect of the glass modifier K_2O in the network formed by glass former V_2O_5-B_2O_3. Electrical conductivity of these glasses was studied for all glasses and results were explained on the basis of Mott's theory of conduction mechanism. A decrease in the conductivity with increase of V-V spacing was observed, which was also confirmed by structural changes observed in the FTIR results of these glasses. The present glasses exhibited the structural changes and confirmed the n-type of semiconducting nature with adiabatic hopping due to polarons.

Keywords: Electrical conductivity, polaron, activation energy, nonbridging oxygen, adiabatic hopping

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