At 298K cation conducting mixed antimonate Na0.8Ni0.6Sb0.4O2 exhibits an O3-type structure, with Na ions in a distorted octahedral coordination, space group R3¯m, a = 3.0496Å, c = 16.4060Å. 23Na nuclear magnetic resonance at 197 to 288K reveals 2 main types of Na atoms in the structure, ascribed to 18g and 3b positions. The temperature increase results in the sites averaging and nuclear magnetic resonance lines narrowing. The activation energy for the motion of Na cations within one site estimated from 23Na nuclear magnetic resonance data was about 1.0kJ/mol at 215 to 288K, much lower than the activation energy of both Na hopping between the sites in a crystallite (about 22kJ/mol at 330 to 370K) and long-range transfer in ceramic material (about 48kJ/mol at 294 to 775K).

Crystal Structure, Local Sodium Environments and Ion Dynamics in Na0.8Ni0.6Sb0.4O2, a New Mixed Antimonite. O.A.Smirnova, J.Rocha, V.B.Nalbandyan, V.V.Kharton, F.M.B.Marques: Solid State Ionics, 2007, 178[23-24], 1360-5