Attaining reduced lattice thermal conductivity and enhanced electrical conductivity in as-sintered pure n-type Bi2Te3 alloy
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Undoped n-type Bi2Te3 bulks were prepared via the liquid state manipulation (LSM) with subsequent ball milling and spark plasma sintering processes. The sample with LSM obtains higher carrier concentration and larger effective mass compared with that without LSM, exhibiting favourable electrical transport properties. More importantly, a much reduced lattice thermal conductivity ~ 0.47 W m−1 K−1 (decreased by 43%) is obtained, due to the enhanced multiscale phonon scattering from hierarchical microstructures, including boundaries, nanograins and lattice dislocations. Additionally, due to the increased carrier concentration and enlarged band gap, the bipolar effect is effectively suppressed in sample BT-LSM. Consequently, zTmax ~ 0.66 is achieved in the sample with LSM at higher temperature of 475 K, almost 22% improvement compared with that of the contrast.
This work was supported by the National Natural Science Foundation of China (Grant No. 51371073), the Natural Science Foundation of Anhui Province (Grant No. 1808085ME108) and Australian Research Council.
Dr. Fang Qiu Zu and Dr. Lan Jun Liu conceived and supervised this study. Xiao Yu Wang designed and carried out the thermoelectric experiments. Xiao Yu Wang and Jin Hui carried out the SPS experiment. Xiao Yu Wang, Bo Xiang and Hong Jing Shang analysed the electrical transport data. Xiao Yu Wang, Dr. Bin Zhu and Dr. Zhong Yue Huang analysed the thermal transport data. Dr. Yuan Yu prepared the TEM specimens. Hui Juan Wang carried out the TEM experiment. Xiao Yu Wang and Hui Juan Wang analysed the TEM data. Dr. Bin Zhu and Run Fei Zhao carried out the Hall measurement experiment. Xiao Yu Wang and Dr. Yuan Yu analysed the Hall data. Xiao Yu Wang, Dr. Fang Qiu Zu and Dr. Zhi Gang Chen wrote the manuscript. All authors have reviewed, discussed and approved the results and conclusions of this article.
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Conflicts of interest
The authors declare that they have no conflict of interest.
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