Raman scattering investigation of Bi2Te3 hexagonal nanoplates prepared by a solvothermal process in the absence of NaOH

Hexagonal Bi2Te3 nanoplates were synthesized by a simple solvothermal process in the absence of NaOH. The composition, morphology and size of the as-prepared products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Raman scattering optical properties of the as-prepared Bi2Te3 nanoplates were investigated by micro-Raman spectroscopy. The Raman spectrum shows that infrared (IR) active mode (A(1u)), which must be odd parity and is Raman forbidden for bulk crystal due to its inversion symmetry, is greatly activated and shown up clearly in Raman scattering spectrum. We attribute the appearance of infrared active (A(1u)) in Raman spectrum to crystal symmetry breaking of Bi2Te3 hexagonal nanoplates. The as-grown Bi2Te3 hexagonal nanoplates, exhibiting novel Raman optical properties compared with bulk crystals, may find potential applications in thermoelectric devices. (C) 2011 Elsevier B.V. All rights reserved.