Electrochemical Synthesis of Bi_1–xSb_x Nanowires with Simultaneous Control on Size, Composition, and Surface Roughness

Abstract

We present the synthesis of Bi1–x Sb x nanowires with controlled composition between x = 0.05 and x = 0.40 over a wide range of diameters (20–100 nm) interesting for the investigation of the enhancement of thermoelectric efficiency via quantum size effects. We find that the relative concentration of Bi and Sb ions in the electrolyte, together with the deposition potential, determines the resulting nanowire composition. Morphology and composition were analyzed using X-ray diffraction, electron microscopy, and energy dispersive X-ray analysis. Two different templates were fabricated to enable the synthesis of nanowires with smooth and rough contour.

Pores with Longitudinal Irregularities Distinguish Objects by Shape

“…21 As shown by our group before, the pores are characterized by significant longitudinal irregularities revealed through resistive-pulse experiments with polystyrene 4 beads as well as metal replicas of the pores. 16,22,23,24 The diameter undulations of PET pores are attributed to the laminar structure of the films, and penetration of the etchant between the strata. 25 Two types of silica rods 26 with diameters of ~220 nm and lengths of 590 and 1950 nm, respectively were detected as they electrokinetically passed through single pores with an average opening diameter of ~1 µm.…”

Characterization and properties of micro- and nanowires of controlled size, composition, and geometry fabricated by electrodeposition and ion-track technology

“…6): (1) A sharp decrease of the current at the beginning of the process attributed to the creation of the diffusion layer; (2) nanowire growth inside the channels with nearly constant current; (3) more or less sharp current increase when the material reaches the top side of the membrane and caps start to grow on top; and (4) if the process is continued, the caps grow further and eventually form a continuous layer. Current–time characteristics displaying these four distinct regions have been reported for the growth of Cu [52], Au [53], Bi [56], Pt [55], Bi 1− x Sb x [60], Bi 2 Te 3 [58], and Ni nanowires among others. The integral of the I – t curves between the beginning of the deposition and the transition to zone 3 corresponds to the charge Q exp applied during the growth process.…”

“…Coarse- and fine-tuning of the Sb concentration was achieved by selecting proper electrolyte composition and potential [60]. Fig.…”

“…With increasing Sb concentration, the d -spacings belonging to the {012} lattice planes decrease, as evident by white lines in the HRTEM images (Figures 10a–d). XRD investigations on the preferred crystallographic orientation of Bi 2 Te 3 and Bi 1− x Sb x nanowires grown in templates are described in references [58,60]. …”

“…(e) Corresponding EDX spectra, indicating the following Sb concentration in the wires x: 0.07, 0.18, 0.26 and 0.41. Adapted with permission from [60] – Copyright 2011 American Chemical Society.…”