摘要
Although traditional ferroelectric materials are usually dielectric and nonconductive,GeTe is a typical ferroelectric semiconductor,possessing both ferroelectric and semiconducting properties.GeTe is also a widely studied thermoelectric material,whose performance has been optimized by doping with various elements.However,the impact of the ferroelectric domains on the thermoelectric properties remains unclear due to the difficulty to directly observe the ferroelectric domains and their evolutions under actual working conditions where the material is exposed to high temperatures and electric currents.Herein,based on in-situ investigations of the ferroelectric domains and domain walls in both pure and Sb-doped GeTe crystals,we have been able to analyze the dynamic evolution of the ferroelectric domains and domain walls,exposed to an electric field and temperature.Local structural heterogeneities and nano-sized ferroelectric domains are generated due to the interplay of the Sb^(3+)dopant and the Ge-vacancies,leading to the increased number of charged domain walls and a much improved thermoelectric performance.This work reveals the fundamental mechanism of ferroelectric thermoelectrics and provides insights into the decoupling of previously interdependent properties such as thermo-power and electrical conductivity.
GeTe是一种典型的铁电半导体,其性能可以通过掺杂各种元素进行优化.然而,由于难以直接观察铁电畴及其在温度和电流的实际工作条件下的演变,因此铁电畴壁对热电性能的影响仍然未知.本工作基于对未掺杂的和Sb掺杂的GeTe晶体中铁电畴和铁电畴壁的原位实验研究,探究了铁电畴和铁电畴壁在外加电场和温度下的动态演化.由于掺杂引入的Sb^(3+)和Ge空位的相互作用,产生了局部结构异质性,引入纳米尺寸的铁电畴,使畴尺寸减小、带电畴壁密度增大,从而大大提高了热电性能.这项工作揭示了铁电畴壁增强热电半导体性能的基本机制,为高性能热电材料的发展提供了新自由度.
作者
Xiangyu Meng
Shuo Chen
Haoyang Peng
Hui Bai
Shujun Zhang
Xianli Su
Gangjian Tan
Gustaaf Van Tendeloo
Zhigang Sun
Qingjie Zhang
Xinfeng Tang
Jinsong Wu
孟祥雨;陈硕;彭昊阳;白辉;张树君;苏贤礼;谭刚健;Gustaaf Van Tendeloo;孙志刚;张清杰;唐新峰;吴劲松(State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,China;Nanostructure Research Center,Wuhan University of Technology,Wuhan 430070,China;Institute for Superconducting and Electronic Materials,Australian Institute for Innovative Materials,University of Wollongong,Wollongong,NSW 2500,Australia;EMAT(Electron Microscopy for Materials Science),University of Antwerp,Belgium)
基金
supported by the National Natural Science Foundation of China(52072282)
the National Key Research and Development Program of China(2019YFA0704900)
performed at the Nanostructure Research Center(NRC),which is supported by the Fundamental Research Funds for the Central Universities(WUT:2021Ⅲ016GX)。
