Effect of ionic liquid amount (C 8H 15BrN 2) on the morphology of Bi 2Te 3 nanoplates synthesized via a microwave-assisted heating approach

Abstract

Bi 2Te 3 crystals with plate-like morphology have been successfully synthesized via a microwave-assisted heating approach in room temperature ionic liquid (RTIL) of 1-butyl-3-methylimidazolium bromide (C 8H 15BrN 2). Scanning electronic microscopy (SEM) observation of as-synthesized Bi 2Te 3 confirmed their morphology of the hexagonal plates. It was observed that the edge and thickness values of as-synthesized Bi 2Te 3 were in the size of 0.5–2 μm and less than 100 nm, respectively. High-resolution transmission electronic microscopy (HR-TEM) and selected area electron diffraction (SAED) results revealed that the Bi 2Te 3 plates are of single-crystal in nature with the growth direction of 〈 1 1 2 ¯ 0 〉 . In addition, as increasing the amount of ionic liquid, SEM results showed a novel evolution process of Bi 2Te 3 morphologies from mixture of Bi 2Te 3 nanorods and nanoplates to regular hexagonal plates, and then nanoplates with many small flecks. Furthermore, a possible mechanism regarding the formation of Bi 2Te 3 plates was proposed as well on the basis of the experimental results. The power factor of Bi 2Te 3 nanoplates is examined to evaluate its thermoelectric property.