Abstract
The thermal expansion for two compositions of cast and hot-pressed LAST
(Pb–Sb–Ag–Te) n-type thermoelectric materials has been measured
between room temperature and 673K via thermomechanical analysis
(TMA). In addition, using high-temperature X-ray diffraction (HT-XRD),
the thermal expansion for both cast and hot-pressed LAST materials was
determined from the temperature-dependent lattice parameters measured
between room temperature and 623 K. The TMA and HT-XRD determined
values of the coefficient of thermal expansion (CTE) for the LAST
compositions ranged between 20106K1 and 24106K1, which is
comparable to the CTE values for other thermoelectric materials including
PbTe and Bi2Te3. The CTE of the LAST specimens with a higher Ag
content (Ag0.86Pb19Sb1.0Te20) exhibited a higher CTE value than that of the
LAST material with a lower Ag content (Ag0.43Pb18Sb1.2Te20). In addition,
a peak in the temperature-dependent CTE was observed between room
temperature and approximately 450K for both the cast and hot-pressed
LAST with the Ag0.86Pb19Sb1.0Te20 composition, whereas the CTE of the
Ag0.43Pb18Sb1.2Te20 specimen increased monotonically with temperature.
