The ionic conductivities of ion-exchanged compounds were measured in A3Sb3P2O14(A = Na, K, Rb) and A5Sb5P2O20(A = Li, Na, K, Rb) with two-dimensional (2D) layered and three-dimensional (3D) framework structures, respectively. In layered A3Sb3P20O14, the mobility of the cations alone determine the ionic conductivity. In A5Sb5P2O20with framework structure, both the bottleneck size and the mobility of the cations affect the observed ionic conductivity. Partial replacement of Sb by Ta/Nb in the highest conducting K5Sb6P2O20sample lead to improvement of the ionic conductivity by 1 order of magnitude (~10−3 (Ω cm)−1 at 500 °C) in R5Sb2Nb2P2O20. The optimal bottleneck size appears to be in K5Sb3Nb2PO20, since no further improvement in the ionic conductivity is observed in K5Sb2Ta3P2O20, which has a larger bottleneck than K5Sb3Nb2P2O20.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry