Synthesis, structural studies, electrical conductivity and optical properties of new Sb_2−xLn_xTe₃ (Ln: Lu³⁺, Er³⁺ and Ho³⁺) nanomaterials

Abstract

Ln-doped Sb₂Te₃ (Ln: Lu³⁺, Er³⁺, Ho³⁺) nanomaterials were synthesised by a co-reduction method in hydrothermal condition. Powder X-ray diffraction (XRD) patterns indicate that the Ln_xSb_2−xTe₃ crystals (Ln = Lu³⁺, x = 0.00–0.06; Er³⁺ and Ho³⁺ x = 0.00–0.04) are isostructural with Sb₂Te₃. The cell parameter a decreases for Ln_xSb_2−xTe₃ compounds upon increasing the dopant content (x), while c increases. Scanning electron microscopy and transmission electron microscopy images show that doping of Lu³⁺ and Ho³⁺ ions in the lattice of Sb₂Te₃ results in spherical nanoparticles while that in Er³⁺ leads to hexagonal nanoplates, respectively. The electrical conductivity of Ln-doped Sb₂Te₃ is higher than that of pure Sb₂Te₃ and increases with temperature. By increasing the concentration of Ln³⁺ ions, the absorption spectrum of Sb₂Te₃ shows red shifts and some intensity changes. In addition to the characteristic red emission peaks of Sb₂Te₃, emission spectra of doped materials show other emission bands originating from f–f transitions of the Ho³⁺ ions.

Keywords:

• hydrothermal
• luminescent
• thermoelectric
• nanomaterial
• antimony telluride

This work is supported by the Grant 2011-0014246 of the National Research Foundation of Korea.