TEM Measurements on Bi1-xSbx Nanowires
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چکیده
room temperature thermoelectric applications, while bismuth antimony alloys exhibit high efficiencies at liquid nitrogen temperature [3]. The synthesis of bismuth compound nanowires with controlled size and crystallinity, and the systematic study of their thermoelectric properties will thus contribute to better understand the influence of mesoscopic and quantum size effects on the thermoelectric characteristics of nanostructured materials. We have successfully synthesized 20-nm diameter Bi1−xSbx nanowires with different composition by potentiostatic electrochemical deposition in ion track-etched membranes [4] applying the same voltage for all samples. Electrolytes with different relative concentration of Bi and Sb ions (c(Bi) and c(Sb), respectively) were employed. The concentration of Sb in the nanowires (x) was measured with a TEM-EDX system. The EDX spectra showed signals also from Pb and Al probably due to stray radiation and impurities introduced during the preparation for TEM. The values for 1 − x and x are presented in Tab. 1, each representing the average of several measuring spots on nanowires fabricated with the same electrolyte. As a result, the concentration of Sb in the Bi1−xSbx nanowires can be controlled by the concentration of Sb ions in solution, in the case of potentiostatic deposition. HRTEM images revealed that all nanowires were polycrystalline, the average grain size increasing with increasing Sb concentration. This is in agreement with the fact that during deposition of nanowires with higher Sb concentrations, the current density was lower, i. e. the growth rate was slower.
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تاریخ انتشار 2010