Nanostructured AgPb_mSbTe_m+2System Bulk Materials with Enhanced Thermoelectric Performance

Abstract

Nanostructured Ag0.8Pbm+xSbTem+2 (m = 18, x = 4.5) system thermoelectric materials have been fabricated by combining mechanical alloying (MA) and spark plasma sintering (SPS) methods followed by annealing for several days to investigate the effect on microstructure and thermoelectric performance. It was found that appropriate annealing treatment could reduce both the electrical resistivity and the thermal conductivity at the same time, consequently greatly enhancing the thermoelectric performance. A low electrical resistivity of 2 x 10-3 Ohm-cm and low thermal conductivity of 0.89 W m-1 K-1 were obtained for the sample annealed for 30 days at 700 K. The very low thermal conductivity is supposed to be due to the nanoscopic Ag/Sb-rich regions embedded in the matrix. A high ZT value of 1.5 at 700 K has been achieved for the sample annealed for 30 days.

Broad temperature plateau for thermoelectric figure of merit ZT>2 in phase-separated PbTe0.7S0.3

“…The model suggests that the phonon scattering by the nanoscale precipitates shall take the major responsibility for the low k lat , although phonon scatterings by other length-scale sources also contribute. Impressively, the volume density of regular-shaped precipitates of 2.5% K-doped PbTe 0.7 S 0.3 can be estimated as 410 times larger than those of platelet-like precipitates in 2.0% Na-doped Pb 0.96 Sr 0.04 Te 10 and 2.0% Na-doped Pb 0.94 Mg 0.06 Te 11 , although they possess a similar number density (10 23 m À 3 ), and thus phonons with mediate mean free paths can be effectively scattered in the present system 33 . Meanwhile, the atomically ordered layers inside the 4-nm cubic precipitates can additionally scatter phonons with short wavelength.…”

A combinatorial approach to microstructure and thermopower of bulk thermoelectric materials: the pseudo-ternary PbTe–Ag2Te–Sb2Te3 system

“…It should also be noted that the ''LAST-18'' (¼ (PbTe) 0.9 (Ag 0.5 Sb 0.5 Te) 0.1 ) composition is close to the solubility of AgSbTe 2 in the PbTe-rich rocksalt at 325 C. At this or similar compositions, nanoscale precipitation occurs 4,[17][18][19]44,45 depending on the alloy preparation conditions. In cases where the precipitates are AgSbTe 2 , 4,17 the precipitation should be a low temperature phenomenon below 325 C, and should redissolve above this temperature.…”

Field‐Assisted Sintering Technology/Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments

“…Also nanostructured bulk oxides like Ga-doped ZnO, [177,178] TiO 2 , [179] or SiTiO 3 [180] were characterized with respect to their thermoelectric properties and generally show a reduction in thermal conductivity when compared to their polycrystalline reference. A further development is the combination of mechanical alloying and FAST/SPS to produce nanostructured or fine grained compound materials as shown for AgPb m SbTe 2þm [181] Hierarchical nano-and microstructured composite materials fabricated by FAST/SPS exhibit current record values in the thermoelectric efficiency. [182] Tabulated data on selected nanostructured thermoelectric compounds can be found in ref.…”