Shape-Controlled Synthesis of Colloidal Nanorods and Nanoparticles of Barium Titanium Sulfide

Ternary transition-metal sulfides with the general formula (AE)MIVS3 (AE = Ca, Sr, Ba; M = Zr, Ti, Hf) have recently drawn increasing attention because of their optical, electronic, and thermal properties, with possible applications including photovoltaic absorbers and NIR detectors. However, synthetic routes to these materials, especially as nanomaterials, remain limited. Here, we report the synthesis of BaTiS3 as colloidal nanomaterials using a solution-based, wet-chemical approach at temperatures as low as 280 °C through the use of reactive metal amide precursors. We demonstrate that nanoparticles or nanorods with typical aspect ratios of approximately 8:1 (50 nm length, 6 nm width) can be prepared, with synthetic control over the nanocrystal size and shape afforded through the choice of a synthetic method (heat-up or hot injection) and through the modulation of the reaction temperature and concentration. Structural data (powder X-ray diffraction) show the hallmarks of a composite crystal correlated with deviations from the ideal stoichiometry. The BaTiS3 nanorods show a strong and tunable NIR absorbance (∼0. 8 eV), whose energy is correlated to the nanorod structure and stoichiometry. These results provide a proof-of-principle for the synthesis of nanocrystals of this class of materials using solution routes.

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