TY - JOUR
T1 - Spinodal decomposition and nucleation and growth as a means to bulk nanostructured thermoelectrics
T2 - Enhanced performance in Pb1-xSn xTe-PbS
AU - Androulakis, John
AU - Lin, Chia Her
AU - Kong, Hun Jin
AU - Uher, Ctirad
AU - Wu, Chun I.
AU - Hogan, Timothy
AU - Cook, Bruce A.
AU - Caillat, Thierry
AU - Paraskevopoulos, Konstantinos M.
AU - Kanatzidis, Mercouri G.
PY - 2007/8/8
Y1 - 2007/8/8
N2 - The solid-state transformation phenomena of spinodal decomposition and nucleation and growth are presented as tools to create nanostructured thermoelectric materials with very low thermal conductivity and greatly enhanced figure of merit. The systems (PbTe)1-x(PbS)x and (Pb 0.95Sn0.05Te)1-x(PbS)x are not solid solutions but phase separate into PbTe-rich and PbS-rich regions to produce coherent nanoscale heterogeneities that severely depress the lattice thermal conductivity. For x gt; ∼0.03 the materials are ordered on three submicrometer length scales. Transmission electron microscopy reveals both spinodal decomposition and nucleation and growth phenomena the relative magnitude of which varies with x. We show that the (Pb0.95Sn 0.05Te)1-x(PbS)x system, despite its nanostructured nature, maintains a high electron mobility (> 100 cm 2/V·s at 700 K). At x ∼ 0.08 the material achieves a very low room-temperature lattice thermal conductivity of ∼0.4 W/m·K. This value is only 28% of the PbTe lattice thermal conductivity at room temperature. The inhibition of heat flow in this system is caused by nanostructure-induced acoustic impedance mismatch between the PbTe-rich and PbS-rich regions. As a result the thermoelectric properties of (Pb0.95Sn0.05Te) 1-x(PbS)x at x = 0.04, 0.08, and 0.16 were found to be superior to those of PbTe by almost a factor of 2. The relative importance of the two observed modes of nanostructuring, spinodal decomposition and nucleation and growth, in suppressing the thermal conductivity was assessed in this work, and we can conclude that the latter mode seems more effective in doing so. The promise of such a system for high efficiency is highlighted by a ZT ∼ 1.50 at 642 K for x ∼ 0.08.
AB - The solid-state transformation phenomena of spinodal decomposition and nucleation and growth are presented as tools to create nanostructured thermoelectric materials with very low thermal conductivity and greatly enhanced figure of merit. The systems (PbTe)1-x(PbS)x and (Pb 0.95Sn0.05Te)1-x(PbS)x are not solid solutions but phase separate into PbTe-rich and PbS-rich regions to produce coherent nanoscale heterogeneities that severely depress the lattice thermal conductivity. For x gt; ∼0.03 the materials are ordered on three submicrometer length scales. Transmission electron microscopy reveals both spinodal decomposition and nucleation and growth phenomena the relative magnitude of which varies with x. We show that the (Pb0.95Sn 0.05Te)1-x(PbS)x system, despite its nanostructured nature, maintains a high electron mobility (> 100 cm 2/V·s at 700 K). At x ∼ 0.08 the material achieves a very low room-temperature lattice thermal conductivity of ∼0.4 W/m·K. This value is only 28% of the PbTe lattice thermal conductivity at room temperature. The inhibition of heat flow in this system is caused by nanostructure-induced acoustic impedance mismatch between the PbTe-rich and PbS-rich regions. As a result the thermoelectric properties of (Pb0.95Sn0.05Te) 1-x(PbS)x at x = 0.04, 0.08, and 0.16 were found to be superior to those of PbTe by almost a factor of 2. The relative importance of the two observed modes of nanostructuring, spinodal decomposition and nucleation and growth, in suppressing the thermal conductivity was assessed in this work, and we can conclude that the latter mode seems more effective in doing so. The promise of such a system for high efficiency is highlighted by a ZT ∼ 1.50 at 642 K for x ∼ 0.08.
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U2 - 10.1021/ja071875h
DO - 10.1021/ja071875h
M3 - Article
AN - SCOPUS:34547763397
SN - 0002-7863
VL - 129
SP - 9780
EP - 9788
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 31
ER -