Conductivity and dielectric properties of Na2O-K2O-Nb2O5-P2O5 glasses with varying amounts of Nb2O5

•Alkaline niobium phosphate glasses•Conductivity and dielectric properties•Compact and integrated glass structure•Large polarizability of niobium ions

Niobium phosphate glasses with a composition of 15K2O-15Na2O-xNb2O5-(70-x) P2O5 (x = 20, 25, 30, 35, 40) have been prepared using the conventional melt-quenching technique. The influence of Nb2O5 on the structure of the prepared glasses was investigated by infrared spectroscopy. The density, chemical stability and glass transition point of the glasses were measured and compared. The dielectric properties were evaluated using impedance spectroscopy. The results show that the increase of Nb2O5 results in more compact and integrated glass network, which contributes to the observed increases in the density, chemical stability and glass transition point of the glasses. Both the conductivity and dielectric parameters show a significant decrease when Nb2O5 increases from 20–25 mol%. Further increasing Nb2O5 up to 35 mol%, the reductions become small. With the addition of 40 mol% of Nb2O5, the conductivity and dielectric parameters become to increase again. The variations of electric and dielectric parameters are the combined results of the changes of glass network and the polarizability of niobium ions.