S H Yang et al 2008 Nanotechnology 19 245707 doi:10.1088/0957-4484/19/24/245707
S H Yang1, T J Zhu1, T Sun2, J He3, S N Zhang1 and X B Zhao1
Show affiliationsThe thermoelectric properties of (GeTe)x(AgSbTe2)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–AgSbTe2 compounds, should make a slight contribution to the low lattice thermal conductivity of TAGS compounds due to the enhanced mid-frequency phonon scattering.
72.20.Pa Thermoelectric and thermomagnetic effects
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
61.46.-w Structure of nanoscale materials
73.63.-b Electronic transport in nanoscale materials and structures
Condensed matter: electrical, magnetic and optical
Issue 24 (18 June 2008)
Received 14 February 2008, in final form 10 April 2008
Published 12 May 2008
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