Heavy rare-earth element doping can effectively strengthen phonon scattering,suppress the lattice thermal conductivity,and enhance the overall thermoelectric performance of GeTe.However,the large electronegativity dif...Heavy rare-earth element doping can effectively strengthen phonon scattering,suppress the lattice thermal conductivity,and enhance the overall thermoelectric performance of GeTe.However,the large electronegativity difference between rare-earth elements(such as La,Eu,and Gd)and Ge refrains the doping limit of rare-earth elements below 1 mol.%in GeTe.Here,compared with other rare earth elements,Lu was found to have a relatively small radius and electronegativity difference with Ge,which can induce a high doping level in GeTe.The result shows that Lu doping effectively reduces the lattice thermal conductivity from 0.77 W^(−1) m K^(−1) of GeTe to 0.35 W m^(−1) K^(−1) of Ge_(0.98)Lu_(0.02)Te at 673 K,and further induces a high zT value of 1.5 in Ge_(0.98)Lu_(0.02)Te at 673 K.Extra Sb alloying optimizes the carrier concentration from 1.02×10^(21) cm^(−3) of Ge_(0.98)Lu_(0.02)Te to 1.77×10^(20) cm^(−3) of Ge0.90Lu0.02Sb0.08Te,which results in a reasonable power factor of 33.82μW cm^(−1) K^(−2) and a low electrical thermal conductivity of 0.75 W m^(−1) K^(−1) at 673 K in Ge_(0.90)Lu_(0.02)Sb_(0.08)Te.Correspondingly,a peak zT of 1.75 at 673 K and an average zT of 0.92 within the temperature range of 303–723 K are obtained in Ge_(0.9)Lu_(0.02)Sb_(0.08)Te.This study indicates that Lu and Sb co-doping can effectively boost the thermoelectric performance of GeTe-based thermoelectric materials.展开更多
基金supported by the Australian Research Council,the Innovation centre for Sustainable Steel project,and the QUT capacity building professor program.K.Guo thanks the support of the National Key Research and Development Program of China(No.2018YFA0702100)。
文摘Heavy rare-earth element doping can effectively strengthen phonon scattering,suppress the lattice thermal conductivity,and enhance the overall thermoelectric performance of GeTe.However,the large electronegativity difference between rare-earth elements(such as La,Eu,and Gd)and Ge refrains the doping limit of rare-earth elements below 1 mol.%in GeTe.Here,compared with other rare earth elements,Lu was found to have a relatively small radius and electronegativity difference with Ge,which can induce a high doping level in GeTe.The result shows that Lu doping effectively reduces the lattice thermal conductivity from 0.77 W^(−1) m K^(−1) of GeTe to 0.35 W m^(−1) K^(−1) of Ge_(0.98)Lu_(0.02)Te at 673 K,and further induces a high zT value of 1.5 in Ge_(0.98)Lu_(0.02)Te at 673 K.Extra Sb alloying optimizes the carrier concentration from 1.02×10^(21) cm^(−3) of Ge_(0.98)Lu_(0.02)Te to 1.77×10^(20) cm^(−3) of Ge0.90Lu0.02Sb0.08Te,which results in a reasonable power factor of 33.82μW cm^(−1) K^(−2) and a low electrical thermal conductivity of 0.75 W m^(−1) K^(−1) at 673 K in Ge_(0.90)Lu_(0.02)Sb_(0.08)Te.Correspondingly,a peak zT of 1.75 at 673 K and an average zT of 0.92 within the temperature range of 303–723 K are obtained in Ge_(0.9)Lu_(0.02)Sb_(0.08)Te.This study indicates that Lu and Sb co-doping can effectively boost the thermoelectric performance of GeTe-based thermoelectric materials.