Single crystal growth and characterization of nearly stoichiometric LiVO₂

LiVO₂ undergoes an imperfectly understood orbital ordering transition near 500K resulting in a loss of magnetic moment below the transition. Studies of the transition have been hampered by a lack of high-quality stoichiometric single crystals. Here we report the growth and basic characterization of large, nearly stoichiometric LiVO₂ single crystals. The crystals were characterized by magnetic susceptibility, electrical resistivity, differential scanning calorimetry, and specific heat measurements over a temperature range from 2 to 650K. A first-order phase transition with large hysteresis near T_t≈500K was observed in all measurements. An anisotropy of the order of 100 was observed in the in-plane versus out-of-plane resistivity, and the inferred semiconducting energy gap was 0.18eV for T<T_t and 0.14eV for T<T_t. Electron diffraction experiments were performed on LiVO₂ single crystals at temperatures below and above T_t. Superlattice reflections were observed below T_t and disappeared upon heating above the phase transition temperature. Upon cooling below T_t, the supperlattice spots reappeared. Bright field electron micrographs indicate that the crystals develop a roughly hexagonal network of cracks.