High-performance thermoelectric materials
are desirable in the
lower-medium temperature range (450–650 K) for low-grade waste
heat recovery. We report a thermoelectric figure of merit (zT) of
1.9 at 585 K in p-type AgSb1–x
Zn
x
Te2, which
is the highest value measured among the p-type materials
in the 450–650 K range. A high average thermoelectric figure
of merit (zTavg) of 1.3 is achieved in AgSb0.96Zn0.04Te2. Moreover, the AgSb1–x
Zn
x
Te2 sample
exhibits a hardness value of ∼6.3 GPa (nanoindentation), which
is significantly higher than that of the pristine AgSbTe2. Substitution of Zn in AgSbTe2 suppresses the formation
of intrinsic Ag2Te impurity phases, which indeed increases
the thermal and mechanical stability. The lattice thermal conductivity
for AgSb1–x
Zn
x
Te2 samples is reasonably reduced compared to that
of the pristine AgSbTe2 because of the significant solid
solution point defect phonon scattering. Aliovalent Zn2+ doping in Sb3+ sites in AgSbTe2 increases
the p-type carrier concentration, which boosts the
electrical conductivity of AgSb1–x
Zn
x
Te2.
SiO2 thin films (3000 AA) are chemically deposited on a silicon substrate at room temperature. Once densified the films exhibit physical and electrical properties comparable to thermal oxides, C-V studies indicate the presence of mobile positive ions inside the oxide layer.
A model is proposed for calculating the T matrix for Coulomb-distorted separable nuclear potentials without the use of the Gell-Mann–Goldberger two-potential theorem. Analytical expressions for the Jost function and T matrix are presented for the Yamaguchi plus screened Coulomb potential treated in the Ecker–Weizel approximation.
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