Dielectric dispersion impedance spectroscopy and polaron tunneling phenomenon in Au2O3 mixed PbO-B2O3-SeO2:Er2O3 glass ceramics

•PbO-B2O3-SeO2:Er2O3 glass ceramics added with traces of Au2O3 were synthesized.•Characterization studies indicated increasing fraction of defects with Au2O3 content.•Dielectric parameters ε′, M, Z and σac are measured in broad ω temperature T ranges.•ε′ is observed to increase with Au2O3 content due to the space charge polarization.•Mechanism of conduction is analyzed using polaronic tunneling model middle ω region.