Environmentally friendly Mg_(3)Sb_(2)-based materials have drawn intensive attention owing to their promising thermoelectric performance.In this work,the electrical properties of p-type Mg_(3)Sb_(2) are dramatically o...Environmentally friendly Mg_(3)Sb_(2)-based materials have drawn intensive attention owing to their promising thermoelectric performance.In this work,the electrical properties of p-type Mg_(3)Sb_(2) are dramatically optimized by the regulation of Mg deficiency.Then,we,for the first time,found that Zn substitution at the Mg2 site leads to the alignment of px,y and pz orbital,resulting in a high band degeneracy and the dramatically enhanced Seebeck coefficient,demonstrated by the DFT calculations and electronic properties measurement.Moreover,Zn alloying decreases Mg1(Zn)vacancies formation energy and in turn increases Mg(Zn)vacancies and optimizes the carrier concentration.Simultaneously,the Mg/Zn substitutions,Mg vacancies,and porosity structure suppress the phonon transport in a broader frequency range,leading to a low lattice thermal conductivity of~0.47 W m^(-1) K^(-1) at 773 K.Finally,a high ZT of~0.87 at 773 K was obtained for Mg_(1.95)Na_(0.01)Zn_(1)Sb_(2),exceeding most of the previously reported p-type Mg_(3)Sb_(2) compounds.Our results further demonstrate the promising prospects of p-type Mg_(3)Sb_(2)-based material in the field of mid-temperature heat recovery.展开更多
基金This work was funded by the National Natural Science Foundation of China(Nos.52130106,51871082,and 52101247)the Natural Science Foundation of Heilongjiang Province of China(No.ZD 2020E003)the Heilongjiang Touyan Innovation Team Program.Thanks to the support from the Fundamental Research Funds for the Central Universities(FRFCU5710053021 and HIT.OCEF.2021014).
文摘Environmentally friendly Mg_(3)Sb_(2)-based materials have drawn intensive attention owing to their promising thermoelectric performance.In this work,the electrical properties of p-type Mg_(3)Sb_(2) are dramatically optimized by the regulation of Mg deficiency.Then,we,for the first time,found that Zn substitution at the Mg2 site leads to the alignment of px,y and pz orbital,resulting in a high band degeneracy and the dramatically enhanced Seebeck coefficient,demonstrated by the DFT calculations and electronic properties measurement.Moreover,Zn alloying decreases Mg1(Zn)vacancies formation energy and in turn increases Mg(Zn)vacancies and optimizes the carrier concentration.Simultaneously,the Mg/Zn substitutions,Mg vacancies,and porosity structure suppress the phonon transport in a broader frequency range,leading to a low lattice thermal conductivity of~0.47 W m^(-1) K^(-1) at 773 K.Finally,a high ZT of~0.87 at 773 K was obtained for Mg_(1.95)Na_(0.01)Zn_(1)Sb_(2),exceeding most of the previously reported p-type Mg_(3)Sb_(2) compounds.Our results further demonstrate the promising prospects of p-type Mg_(3)Sb_(2)-based material in the field of mid-temperature heat recovery.
