연구홍보포털

논문 초록 (Abstract)

Allotropy is a fundamental concept that has been frequently studied since the mid-1800s. Although the bulk allotropy of elemental solid s is fairly well understood, it remains challenging to reliably produce an allotrope at the nanoscale that has a different crystal structure and accompanies a change in physical properties for specific applicat ions. Here, we demonstrate a "heterostructure" approach to produce allotrope-like bismuth nanowires, where it utilizes the latt ice constant difference between bismuth and tellurium in core/sh ell structure. We find that the resultant strain of [100]-grown Bi nanowires increases the atomic linear density along the c-a xis that has been predicted from theoretical considerations, enabling us to establish a design rule for strain-induced allotropic trans formation. With our >400-nm-diameter nanowires, we measure a thermoele ctric figure of merit ZT of 0.5 at room temperature with reduced thermal conductivity and enhanced Seebeck coefficient, which are pr imarily a result of the rough interface and the reduced band overlap according to ourdensity-functional calculations. (C) 2017 Acta Materia lia Inc. Published by Elsevier Ltd. All rights reserved.