Optical and Electrical Properties of CuO-MnO2-B2O3 Glasses

The optical absorption and transmission spectra in (UV-VIS) have been recorded in the wavelength range 350-800 nm for different compositions of CuO-MnO2-B2O3 glasses. The various optical properties such as absorption coefficient ('), optical energy gap (Eopt), refractive index (no), optical dielectric constant ('), measure of extent of band tailing (E), constant () and ratio of carrier concentration to the effective mass (N/m*) for different glasses have been reported. The effects of composition of glasses on these parameters have been discussed. It has been indicated that a small modification of the glasses can lead to an important change in all the optical properties. These results are interesting showing non linear behaviour for all these parameters investigated. The optical parameters are found to be almost the same for different glasses in the same family. Due to the technological importance of CuO-MnO2-B2O3 glasses, dc-conductivity measurement with increasing concentration of MnO2 (in the range of 5-30 mol%) have been reported in the temperature range of 313-573 K in the present study. A plot of –log  versus 1/T shows two different regions of conduction suggesting two types of conduction mechanisms switching from one type to another occurring at knee temperature. The DC conductivity increases with increase in temperature of the sample and also with increase of mol% of MnO2. Activation energy calculated from both regions (LTR and HTR) is below 1 eV. Thus electrical conduction is electronic. Activation energy in LTR and HTR are temperature independent but composition dependent.