Oxygen-ion Conductivity of Re Tungstates Ln14W4O33 (Ln = Nd, Sm, Gd)

RE tungstates Ln14W4O33 (Ln = Nd, Sm, Gd) with a pseudorhombohedral structure were synthesized in the Ln2O3-WO3 systems, using the method of mechanical activation and subsequent high-temperature annealing at 1450-1600 °C for 4h. It was found that these compounds have oxygen-ion conductivity. Nd14W4O33 demonstrates the maximum of oxygen-ion conductivity (4 × 10
^-4
S / cm at 700 °C). The dependence of the total conductivity on the oxygen partial pressure was investigated for Sm14W4O33. It was shown the range of pure oxygen-ion conductivity at 700 °C is 10
^-17
- 0.21 atm. The conductivity of the samples decreases after prolonged their exposure in water at room temperature due to the diffusion of Ln cations into water.