Synthesis, structure and
properties of lithium-ion conducting lanthanum niobates
with defect perovskite structure
Chem.
Met. Alloys 3
(2010) 90-95
https://doi.org/10.30970/cma3.0124
Anatolii G. BELOUS, Oksana
N. GAVRILENKO, Sofiya D. KOBILYANSKAYA, Oleg I. V’YUNOV, Volodymyr V. TRACHEVSKII, Odile BOHNKE
Solid solutions with defect perovskite
structure have been obtained in the system Li0.5‑yNayLa0.5Nb2O6 at 0
≤ y ≤ 0.5. It has been shown that when sodium
ions substitute for lithium ions, an increase in the unit cell volume of the
defect perovskite is observed. The existence of
lithium ions with different mobility in the system Li0.5‑yNayLa0.5Nb2O6
(0 ≤ y < 0.5) has been shown
by 7Li NMR. A percolation mechanism of the
Li ion diffusion is not observed in this system. The lithium-ion conductivity
in Li0.5‑yNayLa0.5Nb2O6
(at y ≤ 0.43) is higher in
comparison with La0.5Li0.5Nb2O6.
This may be due both to the increased amount of more mobile Li+ ions
in the sodium-substituted samples and to the increase of the cell volume. The
lithium-containing lanthanum niobate La0.5Li0.5Nb2O6
has been obtained by the Pechini method. It has
been shown that the resistance of this sample is lower than that of a sample of
the same composition prepared by the solid-state reaction method.
Structure of the A-site deficient perovskite La2/34/3Nb2O6
(space group Pmmm):
La in position 1a (0 0 0), Nb
in 2t (½ ½
z), O(1) in
1f (½ ½
0), O(2) in 1h (½ ½ ½), O(3) in 2s (½ 0 z), O(4) in 2r (0
½ z), and vacancies in 1c (0 0
½).
Keywords
Sodium-containing lithium–lanthanum niobate/ Lithium ion mobility / Ionic transport / 7Li
NMR / Pechini method