Structural disorder and ionic conductivity in LiVO3:: A neutron powder diffraction study from 340 to 890 K

The structure of the lithium metavanadate LiVO3 has been refined at room temperature from high-resolution neutron powder diffraction data. The unit cell dimensions are a 10.1597((4)), b = 8.4155((3)), c = 5.8843((2)) Angstrom, beta = 110.5051((2))degrees, and V = 471.23((1)) Angstrom (3) in the monoclinic space group C2/c with Z = 8. Conventional R-p and R-wp reliability factors are respectively equal to 0.030 and 0.036. The structure consists of an alternating, along the b-axis, of bands of distorted LiO6 octahedra running parallel to the c-axis which are linked by chains of VO4 tetrahedra which are also parallel to the c-axis. The structural behavior of the ionic conductor LiVO3 has been studied from neutron powder thermodiffractometry in the temperature range 340-890 K in order (i) to confirm the nature of the mobile species, (ii) to characterize the diffusion mechanisms, and (iii) to link the structural disorder existing in LiVO3 to the high observed ionic conductivity. (C) 2001 Academic Press.