Flower-like nanostructure and thermoelectric properties of hydrothermally synthesized La-containing Bi2Te3 based alloys

Single-phase La-containing Bi2Te3 based nanopowders have been synthesized via a hydrothermal route using BiCl3, LaCl3, selenium and tellurium powders as the reactants, NaBH4 as the reductant, NaOH as the pH-value controller and ethylenediaminetetraacetic disodium salt (EDTA) as the additive. The synthesized powders have a flower-like morphology assembled by the side-by-side arrangement of the nano-sheets. Rietveld refinement analyses of crystal structure indicated that the alloyed lanthanum substituted bismuth at the 6c lattice position of Bi2Te3 based compounds. The thermoelectric property measurements of the hot-pressed samples showed that the substituting lanthanum in the Bi2Te3 based compounds was an n-type dopant. A ZT value of about 0.58 has been obtained for the La0.2Bi1.8Te3 alloy at 480 K.