title: Nanostructures in high-performance (GeTe)(x)(AgSbTe(2))(100-x) thermoelectric materials.
abstract: The thermoelectric properties of (GeTe)(x)(AgSbTe(2))(100-x) compounds (x = 75, 80, 85 and 90; TAGS-x) have been studied as a function of temperature from 300 to 720 K. At 720 K the dimensionless figure of merit ZT reaches the state-of-the-art value of 1.53 for TAGS-75 and 1.50 for TAGS-80 and TAGS-85 samples, respectively. But the ZT value of the TAGS-90 sample is only 0.50 at 720 K due to the high carrier concentration. Utilizing high-resolution transmission electron microscope and selected area electron diffraction techniques, we identify a considerable number of nanoscale domains with typical size ∼10 nm in the samples that show high ZT values. It is suggested that the presence of nanoscale domains, like the situation in PbTe-AgSbTe(2) compounds, should make a slight contribution to the low lattice thermal conductivity of TAGS compounds due to the enhanced mid-frequency phonon scattering.
authors.affiliation: State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: S H
authors.initials: SH
authors.lastname: Yang
authors.forename: T J
authors.initials: TJ
authors.lastname: Zhu
authors.forename: T
authors.initials: T
authors.lastname: Sun
authors.forename: J
authors.initials: J
authors.lastname: He
authors.forename: S N
authors.initials: SN
authors.lastname: Zhang
authors.forename: X B
authors.initials: XB
authors.lastname: Zhao