On the structure and ionic conductivity of Bi2V1-xTix/2Gdx/2O5.5-δ system

In this work, Ti and Gd co-doped Bi2VO5.5 compounds have been reported. The structural analysis reveals suppression of phase transition in the co-doped system. The conductivity plots of Bi2V1-xTix/2Gdx/2O5.5-δ (0 ≤ x ≤ 0.225) carry two distinct segments: Below and above ∼ 425 °C. Below this temperature, the ionic conductivity is higher for all the doped compounds than the parent specimen Bi2VO5.5, with the highest value of conductivity for x = 0.175. At higher temperatures, though, conductivity is lower than the parent compound for all the specimens. The enhancement observed in the conductivity is explained by structural and Raman spectra analysis and is corroborated with the electrochemical impedance analysis. •Bi2V1-xGdx/2Tix/2O5.5-δ (0.125 ≤ x ≤ 0.225) polycrystalline ceramic samples have been synthesized by standard SSR technique.•The structural modification concerning to dopant concentration has been studied through XRD & Raman spectroscopy.•Role of Ti & Gd for the stabilization of high conducting γ -phase has been analysed.•Ionic conductivity is found higher than parent for all the doped compounds below ∼425°C & maximum is obtained for x = 0.175.