Thermoelectric power of the thallium-based superconductor Tl2Ba2Ca2Cu3O10- delta

Impurity metallic conduction below the critical concentration of metal-insulator transition in Fe1-xCoxSi

Analysis on very detailed measurements of resistivity (ρ) and thermoelectric power (S) of magnetic impurity (Co) substituted iron silicide (FeSi) has been presented in this report. The impurity valence electrons of Co dominate the whole physical properties at low temperatures below 35 K, below the critical concentrationx_c(≈0.02). The negative thermopower and the positive slope in the resistivity at low temperatures are exciting and show that the system is not entirely insulator below the critical concentration of metal-insulator transition (x_c). So, due to the external impurity electrons, the system's magnetic ground state could change considerably compared to the parent compound FeSi. This report may help unveil the interesting low-temperature transport properties betweenx= 0 andx= 0.04 (Fe1-xCo_xSi). Two band model and variable range hopping model were employed to explain the low-temperature electrical and thermal transport properties.

Enhanced Thermoelectric Performance of Novel Reaction Condition-Induced Bi2S3-Bi Nanocomposites

This is the first report on the enhanced thermoelectric (TE) properties of novel reaction-temperature (T_Re) and duration-induced Bi₂S₃-Bi nanocomposites synthesized using a facile one-step polyol method. They are well characterized as nanorod composites of orthorhombic Bi₂S₃ and rhombohedral Bi phases in which the latter coats the former forming Bi₂S₃-Bi core-shell-like structures along with independent Bi nanoparticles. A very significant observation is the systematic reduction in electrical resistivity ρ with a whopping 7 orders of magnitude (∼10⁷) with just reaction temperature and duration increase, revealing a promising approach for the reduction of ρ of this highly resistive chalcogenide and hence resolving the earlier obstacles for its thermoelectric application potentials in the past few decades. Most astonishingly, a TE power factor at 300 K of the highest Bi content nanocomposite pellet, made at 27 °C using ∼900 MPa pressure, is 3 orders of magnitude greater than that of hot-pressed Bi₂S₃. Its highest ZT at 325 K of 0.006 is over twice of that of similarly prepared CuS or Ag₂S-based nanocomposites. A significantly improved TE performance potential near 300 K is demonstrated for these toxic-free and rare-earth element-free TE nanocomposites, making the present synthesis method as a pioneering approach for developing enhanced thermoelectric properties of Bi₂S₃-based materials without extra sintering steps.

Metal-like electrical conductivity in LaxSr2−xTiMoO6 oxides for high temperature thermoelectric power generation

Increasing electrical conductivity in oxides, which are inherently insulators, can be a potential route in developing oxide-based thermoelectric power generators with higher energy conversion efficiency.