Structural and dielectric properties of Li2O-ZnO-BaO-B2O3-CuO glasses

Glass samples of the system (15Li(2)O-30ZnO-10BaO-(45 - x)B2O3-xCuO where x = 0, 5, 10 and 15 mol%) were prepared by using the melt quenching technique. A number of studies, viz. density, differential thermal analysis, FT-IR spectra, a.c. conductivity and dielectric properties (constant epsilon phi, loss tan delta, a.c. conductivity, sigma(ac), over a wide range of frequency and temperature) of these glasses were carried out as a function of copper ion concentration. The analysis of the results indicate that the density increases while molar volume decreases with increasing of copper content indicates structural changes of the glass matrix. The glass transition temperature, T-g, and crystallization temperature, T-c, increase with the variation of concentration of CuO referred to the growth in the network connectivity in this concentration range, while glass-forming ability parameter (T-c - T-g) decreases with increasing CuO content, indicates an increasing concentration of copper ions that take part in the network-modifying positions. The FT-IR spectra evidenced that the main structural units are BO3, BO4, and ZnO4. The structural changes observed by varying the CuO content in these glasses and evidenced by FTIR investigation suggest that the CuO plays a network modifier role in these glasses while ZnO plays the role of network formers. The dielectric constant decreased with increase in temperature and CuO content. The variation of a.c. conductivity with the concentration of CuO passes through a maximum at 5 mol%. In the high temperature region, the a.c. conduction seems to be connected with the mixed conduction viz., electronic conduction and ionic conduction.