Mg-doping effect on structural and magnetic properties on two-dimensional triangular lattice LiVO2.

Transition metal compounds with two-dimensional triangular lattice, such as LiVO₂, are of particular interest, because they exhibit peculiar structural and magnetic behavior involving the frustration present in these oxides. An orbital ordering transition occurs near 500 K, which leads to a suppression of magnetic moment below the phase transition temperature Tt. We synthesized a series of Mg-doped LiVO₂ single-phase samples and reported their structural and magnetic properties. The samples were characterized by x-ray diffraction, scanning electron microscope, differential scanning calorimetry, electrical resistivity, magnetic susceptibility, and specific heat measurement. For Mg-doped samples Li_1-xMg_xVO₂ (x=0, 0.05, 0.10, and 0.15), the structural analysis show that, with increasing x, the lattice constants change monotonously; in the a-b plane, the lattice expands; while in the c-axis direction, the lattice is compressed. Substitution of Li with Mg ions results in the degeneration of two-dimensional characteristics and the distortion of the VO₆ block, which significantly influence magnetic properties. The magnetic phase transition temperature falls with increasing x. The Mg-dopants play an important role on breaking the original moment equilibrium and suppressing the magnetic frustration. [ABSTRACT FROM AUTHOR]