Microstructural, dielectric and spectroscopic properties of Li2O–Nb2O5–ZrO2–SiO2 glass system crystallized with V2O5

Li2O–Nb2O5–ZrO2–SiO2 glasses mixed with different concentrations of V2O5 were crystallized. The samples were characterized by XRD, SEM and DTA techniques. The SEM pictures indicated that the samples contain well defined and randomly distributed crystal grains. The X-ray diffraction studies have revealed the presence of several crystalline phases in these samples. Optical absorption, ESR and photoluminescence spectral studies on these samples have indicated that a considerable proportion of vanadium ions do exist in V4+ state in addition to V5+ state and the redox ratio seems to be increasing with increase in the concentration of crystallizing agent V2O5. The infrared spectral studies have pointed out the existence of conventional SiO4, ZrO4, NbO6, VO structural units in the glass ceramic network. The study of dielectric properties suggested a decrease in the insulating character of the glass ceramics with increase in the crystallizing agent. A.C. conductivity in the high temperature region seems to be connected mainly with the polarons involved in the process of transfer from V4+↔V5+ ions.

Research highlights
► Li2O–Nb2O5–ZrO2–SiO2 glasses mixed with different concentrations of V2O5 were crystallized.
► Spectroscopic studies on these samples have indicated vanadium ions do exist in V4+ state along with V5+.
► Redox ratio is found increasing with increase in the concentration of crystallizing agent.
► The dielectric studies suggested a decrease of insulating character of the samples with V2O5 content.