Effect of substituting iron on structural, thermal and dielectric properties of lithium borate glasses

• There is increase in NBOs with iron content.
• FTIR spectra supported the results predicted by density.
• Glass stability has been examined.
• Iron shows “blocking effect” on migration of mobile ions.
• Internal Circuit varies with temperature and composition.

Glasses with composition xFe2O3·(30 − x)Li2O·70B2O3 (x = 0, 2, 5, 7 and 10 mol%) were prepared via melt-quenching technique and their physical, thermal and dielectric properties are discussed. XRD was carried out to confirm the amorphous nature of prepared glasses. Density (ρ) and molar volume (Vm) were found to increase with increase in Fe2O3 content. Infrared absorption spectra depicted that Fe2O3 is acting as a network modifier. DTA has been carried out to determine glass transition temperature (Tg) and crystallization temperature (Tx). Electrical properties have been studied using impedance spectroscopy and dc conductivity. The dc conductivity decreases and activation energy increases on replacing Li+ ions with Fe3+. The impedance measurements reveal that the total conductivity obeys Jonscher’s power law. Study of the equivalent circuit analysis up to a temperature of 523 K shows a significant change in the equivalent circuitry with change in temperature and composition.

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