Abstract
The Ⅳ-Ⅵ compound GeTe is considered as a promising alternative to the toxic PbTe for high-efficiency mid-temperature thermoelectric applications.However,pristine GeTe suffers from a high concentration of Ge vacancies,resulting in an excessively high hole concen-tration(＞1 × 1021 cm-3),which greatly limits its thermoelectric enhancement.To address this issue,CuBiTe2 alloying is introduced to increase the formation energy of Ge vacancies in GeTe,thereby inhibiting the high carrier concentration.The carrier scattering caused by the electronegativity difference between different elements is suppressed due to the similar electronegativity of Cu and Ge atoms.A relatively high hole mobility is obtained,which ultimately leads to a high power factor.Addition-ally,by introducing Se as an alloying element at the anionic site in GeTe,dense point defects with mass/strain-field fluctuations are induced.This contributes to the strengthening of phonon scattering,thereby reducing the lattice thermal conductivity from 1.44 W·m-1·K-1 for pristine GeTe to 0.28 W·m-1·K-1 for Ge0.95Cu0.05Bi0.05-Te0.9Se0.15 compound at 623 K.
基金项目
国家重点研发计划(2018YFA0702100)
国家自然科学基金(U21A2054)
Key Discipline of Materials Science and Engineering,Bureau of Education of Guangzhou(202255464)
NETL
NSTL
万方数据