In order to explain the unique thermoelectric properties of bulk nanocomposite p-type bismuth antimony telluride, its structural and electrical properties are investigated using transmission electron microscopy (TEM) and atomic force microscopy with a conductive probe (C-AFM). The material is observed to contain both nano- and micro-sized grains with sizes varying from 10 nm to 3 m. This unique structure promotes phonon scattering, thereby decreasing the thermal conductivity to below 1 W mK -1 at room temperature. Moreover, the C-AFM data show that the electrical conductivity of nanosized grains is higher than the bulk value and reaches 1600 S cm -1. This results in a moderate increment of the overall electrical conductivity, thereby increasing the figure of merit (ZT) up to 1.4 at 100 °C. In addition to demonstrating a powerful scanning probe microscopy (SPM) based investigation technique that requires minimal sample preparation, our findings contribute towards better understanding of the enhancement of thermoelectric properties of nanocomposite thermoelectric materials.
ASJC Scopus subject areas
- Materials Science(all)