Investigation of structural and impedance spectroscopic properties of borate glasses with high Li+ concentration

Abstract

Lithium borate glasses prepared by melt-quench technique have been studied with a view to ascertain their structural and electrical properties. FTIR analysis of the present samples reveals the absence of boroxol rings, presence of structural units of lithium formed with oxygen and increase in the number of Non-Bridging Oxygens (NBOs) in the glass system. The real and imaginary parts of dielectric constant increase with frequency and temperature arises due to interfacial ionic polarization. The non-exponential Kohlrausch-Williams-Watts (KWW) function has been found to follow by the imaginary part of electric modulus, thereby confirming its applicability. The fitting of data of ac conductivity as per Jonscher's universal power law indicates hoppable ion concentration dependent upon temperature and Li2O content. The analysis is further supported by the variations of ac-conductivity as well as the activation energy for dc conductivity. A decrease in impedance and increase in the space charge polarization is observed with increasing Li2O concentration. Further, the electrical behavior of samples has been investigated via an impedance equivalent circuit corresponding to the Nyquist plot.