Single crystal growth and characterization of nearly stoichiometric LiVO2

LiVO2 undergoes an imperfectly understood orbital ordering transition near 500 K 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 650 K. A first-order phase transition with large hysteresis near Tt≈500 K 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 0.18 eV for T<Tt and 0.14 eV for T<Tt. Electron diffraction experiments were performed on LiVO2 single crystals at temperatures below and above Tt. Superlattice reflections were observed below Tt and disappeared upon heating above the phase transition temperature. Upon cooling below Tt, the supperlattice spots reappeared. Bright field electron micrographs indicate that the crystals develop a roughly hexagonal network of cracks.