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Effect of Sb deficiency on the thermoelectric properties of Zn4Sb3
We have investigated the effect of Sb-deficiency on the thermoelectric figure
of merit (zT) of Zn4Sb3 prepared by solid state reaction route. At high
temperatures, the Seebeck coefficient (S) and electrical conductivity
({\sigma}) increase with increase in Sb deficiency whereas the thermal
conductivity (\k{appa}) decreases giving rise to an increase in the overall zT
value. The observations suggest that creation of vacancies could be an
effective route in improving the thermoelectric properties of Zn4Sb3 system.
This coupled to nanostructuring strategy could lead to the ultimate maximum
value of zT in this system for high temperature thermoelectric applications
Growth, Characterization, Vortex Pinning and Vortex Flow Properties of Single Crystals of Iron Chalcogenide Superconductor FeCrSe
We report the growth and characterization of single crystals of iron
chalcogenide superconductor FeCrSe. There is an enhancement of the
superconducting transition temperature (T) as compared to the T of the single crystals of the parent compound FeSe by about 25%.
The superconducting parameters such as the critical fields, coherence length,
penetration depth and the Ginzburg-Landau parameter have been estimated for
these single crystals. Analysis of the critical current data suggests a
fluctuation in electronic mean free path induced () pinning mechanism
in this material. Thermally activated transport across the superconducting
transition in the presence of external magnetic fields suggests a crossover
from a single vortex pinning regime at low fields to a collective flux creep
regime at higher magnetic fields. The nature of charge carriers in the normal
state estimated from the Hall effect and thermal transport measurements could
provide crucial information on the mechanism of superconductivity in Fe-based
materials.Comment: 2 additional figures, additional discussion on nature of charge
carrier
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