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A crystal structure investigation of the low temperature Li 2 SnO 3 modification has been carried out. X-ray, neutron powder and electron diffraction data showed that this compound crystallizes in a monoclinic unit cell with parameters: a = 5.3033(2)Å, b = 9.1738(3)Å, c = 10.0195(2)Å, β~100.042(2)º and has stacking disorder along the c-axis. Simulation of diffraction patterns with different stacking faults mainly reveal the presence of rotational stacking faults with a probability of about 40% .

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A comparative analysis of 6,7 Li NMR spectra is performed for the samples of monoclinic lithium titanate obtained at different synthesis temperatures. In the 7 Li NMR spectra three lines are found, which differ in quadrupole splitting frequencies Q Q and according to ab initio EFG calculations are assigned to three crystallographic sites of lithium: Li1 (Q Q a 27 kHz); Li2 (Q Q a 59 kHz); Li3 (Q Q a 6 kHz). The dynamics of lithium ions is studied in a wide temperature range from 300 K to 900 K. It is found that the narrowing of 7 Li NMR spectra as a result of thermally activated diffusion of lithium ions in the low-temperature Li 2 TiO 3 sample is observed at a higher temperature in comparison with a sample of high-temperature lithium titanate. Based on the analysis of 6 Li NMR spectra it is assumed that there is mixed occupancy of lithium and titanium sites in the corresponding layers of the crystal structure of low-temperature lithium titanate, which hinders lithium ion transfer over regular crystallographic sites.

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The crystal structure, electronic properties, and sodium diffusion mechanism in Na 5 Sc(MoO 4 ) 4 were investigated using the powder X-ray diffraction, nuclear magnetic resonance, and electrical conductivity measurements, as well as ab initio calculations. Na 5 Sc(MoO 4 ) 4 belongs to the family of alluaudite-type oxides Na x M y (AO 4 ) 3 (M = In, Sc, Mg, Cd, Zn, Mn, Fe, Co, and Ni; A = Mo, W, P, As, and S), which are now considered as promising materials for sodium-ion batteries. Our results demonstrate a considerable difference in the mechanism of Na + ion transport in Na 5 Sc(MoO 4 ) 4 and in previously studied alluaudite oxides, where one-dimensional sodium diffusion was suggested to occur through channels along the c-axis. The Na + motion in Na 5 Sc(MoO 4 ) 4 is found to be rather two-dimensionally occurring along the bc-plane. We believe that filling of the M-sublattice plays a key role in the mechanism of Na + ion diffusion in alluaudite compounds. In particular, in Na 5 Sc(MoO 4 ) 4 characterized by a low Sc-occupancy of the M-sublattice, the sodium ions located far from scandium are the first to be activated with increasing temperature and the activation energy for their jumps, E a ≤ 0.3 eV, has one of the lowest values among Na-conductive materials.