Synthesis and structural analysis of angled Te nanocrystals

In this paper, a new direct method to prepare angled Te nanocrystals (NCs) in the isotropic thiol-ligand system from the transformation of MA-stabilized CdTe nanoparticles (NPs) induced by the post-addition of L-cysteine was presented, without removing aforehand the protective shell of organic stabilizer. Besides nanorods, angled Te nanocrystals, including nanocheckmarks, X-shaped, nanomoths, y-shaped, and so on, also were obtained. By means of high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED) and powder X-ray diffractometry (XRD), we further investigated intensively the internal crystal structure of angled Te NCs and the growth direction of the arms in this study. The experimental results obtained show that the preferential growth direction of either arms in nanocheckmarks is along the[001] direction of trigonal Te, and the corresponding contact plane should be (112) of hexagonal lattice. In the meantime, these results also confirm that L-cysteine not only can be used as the stabilizer for the synthesis of aqueous CdTe NPs as reported previously, but also can act as a strong complexing agent like EDTA, inducing the decomposition of CdTe NPs, i.e. the transformation from CdTe NPs to Te nanocrystals. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)