摘要
(Bi,Sb)_(2)(Te,Se)_(3) alloys are widely used commercial thermoelectric(TE)materials for solid-state refrigeration around room temperature.The composition-induced structural phase transition could be realized by varying the compositions in these alloys,which may largely alter the electronic structure and phonon dispersion.Among them,the Se-alloyed Sb_(2)Te_(3) accompanied with structural transition is seldom reported.Herein,the interrelations of Se-alloying induced changes in structural phase transition,band structure and TE properties of p-type zone-melted Sb_(2)Te_(3-x)Se_(x)(x=1.5-2.4)alloys near phase transition boundary are systematically investigated.The results demonstrate that Sb_(2)Te_(3-x)Se_(x) shows a structural transition from a rhombohedral phase to mixed structure at x=2.0.The carrier concentration and bandgap at room temperature of Sb_(2)Te_(3)-xSex(x=1.5-2.4)constantly decrease with increasing Se contents x.The zT peak of the Sb_(2)TeSe_(2) matrix is improved and shifted to higher temperature by optimizing carrier concentration via Ag doping.A maximum zT of~0.4 is obtained at 680 K in Sb_(1.97)Ag_(0.03)TeSe_(2) alloy,about 100% enhancement compared with the undoped sample.
基金
financially supported by the National Science Foundation of China(No.51871199,51861145305,51572237,61534001)
the Zhejiang Provincial Natural Science Foundation(No.LZ17E020003)
the Fundamental Research Funds for the Central Universities(No.2017XZZX001-04,2017QNA4011)
the 111 Project(No.B16042).
