Lithium conductivity in an Li-bearing double-ring silicate mineral, sogdianite
Journal of Solid State Chemistry 180(4): 1306-1317
The crystal structure of an Li-bearing double-ring silicate mineral, sogdianite ((Zr1.18Fe0.553+ Ti-0.24 Al-0.03)(gamma(1.64),Na-0.36)K-0.85[Li3Si12O30], P6/mcc, a approximate to 10.06 A, c approximate to 14.30 A, Z = 2), was investigated by neutron powder diffraction from 300 up to 1273 K. Rietveld refinements of displacement parameters revealed high anisotropic Li motions perpendicular to the crystallographic c-axis, indicating an exchange process between tetrahedral T2 and octahedral A sites. AC impedance spectra of a sogdianite single crystal (0.04 x 0.09 x 0.25 cm(3)) show that the material is an ionic conductor with conductivity values of a = 4.1 x 10(-5) S cm(-1) at 923 K and 1.2 x 10(-3) S cm(-1) at 1219 K perpendicular to the c-axis, involving two relaxation processes with activation energies of 1.26(3) and 1.08(3) eV, respectively. (C) 2007 Published by Elsevier Inc.