Molten salt flux synthesis of La^sub 5^Ti^sub 2^CuS^sub 5^O^sub 7^ towards elongated single crystallites

The preparation of La5Ti2CuS5O7 single crystallites was attempted in various alkali metal halide molten salts used as flux materials. The average size of La5Ti2CuS5O7 crystallites produced was found to correlate with La5Ti2CuS5O7 solubility in the flux materials. For elongated La5Ti2CuS5O7 crystallites, CsCl melted at 1273 K was an optimal flux material. Needlelike crystallites with an average diameter of 0.8 ± 0.2 µm and an average length of 109.7 ± 19.2 µm were obtained after treatment for ~48 h. Transmission electron microscopy revealed the monocrystalline nature of the needlelike La5Ti2CuS5O7 crystallites with a specific orientation. The quality of the crystallites of La5Ti2CuS5O7 and similar oxysulfide materials indicates their promising future application as transparent conductors, low-dimensional magnetic materials, and photocatalysts.