Ionic conduction in Zn2+-doped ZrP2O7 ceramics at intermediate temperatures

A novel series of Zr1 − xZnxP2O7 (x = 0.00, 0.03, 0.06, 0.1) was prepared by a solid state reaction method. XRD patterns indicated that all the samples exhibited a single cubic phase structure except Zr0.9Zn0.1P2O7. The conduction behavior was investigated using various electrochemical methods including ac impedance spectroscopy, isotope effect, gas concentration cells etc. in the temperature range of 300–600 °C. The conductivities were affected by the doping levels, and increased in the order: σ (x = 0.00) < σ (x = 0.03) < σ (x = 0.1) < σ (x = 0.06). Zr0.94Zn0.06P2O7 exhibited the highest conductivities of 1.85 × 10− 4 S·cm− 1 in wet hydrogen and 1.02 × 10− 4 S·cm− 1 in dry air at 600 °C. Isotope effect confirmed the proton conduction of the samples under water vapor-containing atmosphere. It was found that the ceramic samples were mixed conductors of oxide ionic and electron hole in dry oxygen-containing atmosphere. Whereas the ceramic samples were almost pure ionic conductors, and the ionic conduction was mainly contributed to proton and partially to oxide ionic in wet hydrogen atmosphere.