Molten salt flux synthesis of La₅Ti₂CuS₅O₇ towards elongated single crystallites

Abstract

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.

One-dimensional Anisotropic Electronic States in Needle-shaped La5Ti2CuS5O7 Single Crystals Grown in Molten Salt in Bridgman Furnace

“…The average length of top-ten crystals found in this product powder is 1.2 ± 0.2 mm, and the average diameter is 2.9 ± 0.7 μm. Both the length and the diameter using the present method is superior by nearly one order of magnitude to the regular CsCl flux molten salt method, which provided average values of 109.7 ± 19.2 μm in length and 0.8 ± 0.2 μm in diameter.…”

“…The development for fabrication of high-quality, large-sized crystallites has been in progress. Bulky amounts of La 5 Ti 2 CuS 5 O 7 have been mostly synthesized by high-temperature solid-state reaction of mixtures of the precursor compounds. ,,,, We recently attempted to grow La 5 Ti 2 CuS 5 O 7 crystallites from the precursor metal oxides/sulfides in various molten alkali metal halides . As a result, La 5 Ti 2 CuS 5 O 7 was grown in CsCl flux into crystallites with an average length of 110 μm and average diameter of 0.8 μm.…”

Understanding the Photocatalytic Activity of La5Ti2AgS5O7 and La5Ti2CuS5O7 for Green Hydrogen Production: Computational Insights

“…The shape of the LTC Wulff construction can be compared to molten-salt flux grown crystallites reported by Iwase et al 19,20 While the (010) end of the Wulff shape resembled the blunt ends of crystallites well, the length of the predicted columnar particle was very different. This was most likely due to the flux-mediated method used in the experimental work favoring elongation of crystals in the b-direction, something that cannot be accounted for during the construction of the Wulff shape.…”

“…32 All zero-dipole symmetric slabs up to a maximum Miller index of two were considered in this study. The (001) surface was added, and the (1−12) and (−211) surfaces replaced the (112) and (211) surfaces as they were observed on selected area electron diffraction (SAED) patterns by Iwase et al 19,20 The pairs of positive and negative index surfaces were identical, but the negative index slabs were included for consistency with experimentally reported nomenclature. Slab calculations used the same energy cut off as bulk, with k-point meshes derived from the bulk, keeping the same reciprocal space spacing.…”

“…Neither system displays the extent of anisotropy described by Iwase et al, likely due to the experimental conditions favoring elongation of crystals. 19,20 The surface energy anisotropy, based on the coefficient of variation from weighted surface energy, is 0.098 for LTA and 0.111 for LTC, making LTC ever so slightly more anisotropic. Both materials are predicted to be more anisotropic than 88% of the elemental crystals.…”