Density-Dependence of Surface Transport in Tellurium-Enriched Nanograined Bulk Bi Te.

Three-dimensional topological insulators (3D TI) exhibit conventional parabolic bulk bands and protected Dirac surface states. A thorough investigation of the different transport channels provided by the bulk and surface carriers using macroscopic samples may provide a path toward accessing superior surface transport properties. Bi Te materials make promising 3D TI models; however, due to their complicated defect chemistry, these materials have a high number of charge carriers in the bulk that dominate the transport, even as nanograined structures.

Europium Clustering and Glassy Magnetic Behavior in Inorganic Clathrate-VIII EuGaGe.

The temperature- and field-dependent, electrical and thermal properties of inorganic clathrate-VIII EuGaGe were investigated. The type VIII clathrates were obtained from the melt of elements as reported previously. Specifically, the electrical resistivity data show hysteretic magnetoresistance at low temperatures, and the Seebeck coefficient and Hall data indicate magnetic interactions that affect the electronic structure in this material.

High-Performance n-Type Ge-Free Silicon Thermoelectric Material from Silicon Waste.

Silicon waste (SW), a byproduct from the photovoltaic industry, can be a prospective and environmentally friendly source for silicon in the field of thermoelectric (TE) materials. While thermoelectricity is not as sensitive toward impurities as other semiconductor applications, the impurities within the SW still impede the enhancement of the thermoelectric figure of merit, . Besides, the high thermal conductivity of silicon limits its applications as a TE material.

Interface-Dominated Topological Transport in Nanograined Bulk Bi Te.

3D topological insulators (TI) host surface carriers with extremely high mobility. However, their transport properties are typically dominated by bulk carriers that outnumber the surface carriers by orders of magnitude. A strategy is herein presented to overcome the problem of bulk carrier domination by using 3D TI nanoparticles, which are compacted by hot pressing to macroscopic nanograined bulk samples.

Reduced Lattice Thermal Conductivity for Half-Heusler ZrNiSn through Cryogenic Mechanical Alloying.

The ZrNiSn-based half-Heusler compounds are promising for thermoelectric applications in the mid-to-high temperature range. However, their thermoelectric performance was greatly limited due to the remaining high thermal conductivity, especially the lattice thermal conductivity. Herein, we report the synthesis of pristine half-Heusler ZrNiSn through direct mechanical alloying at a liquid nitrogen temperature (i.

Towards tellurium-free thermoelectric modules for power generation from low-grade heat.

Thermoelectric technology converts heat into electricity directly and is a promising source of clean electricity. Commercial thermoelectric modules have relied on BiTe-based compounds because of their unparalleled thermoelectric properties at temperatures associated with low-grade heat (<550 K). However, the scarcity of elemental Te greatly limits the applicability of such modules.

Influence of Nanoparticle Processing on the Thermoelectric Properties of (Bi Sb ) Te Ternary Alloys.

The synthesis of phase-pure ternary solutions of tetradymite-type materials (Bi Sb ) Te (x=0.25; 0.50; 0.

Entropy of Conduction Electrons from Transport Experiments.

The entropy of conduction electrons was evaluated utilizing the thermodynamic definition of the Seebeck coefficient as a tool. This analysis was applied to two different kinds of scientific questions that can-if at all-be only partially addressed by other methods. These are the field-dependence of meta-magnetic phase transitions and the electronic structure in strongly disordered materials, such as alloys.

Synergetic Enhancement of Thermoelectric Performance by Selective Charge Anderson Localization-Delocalization Transition in n-Type Bi-Doped PbTe/AgTe Nanocomposite.

Considerable efforts have been devoted to enhancing thermoelectric performance, by employing phonon scattering from nanostructural architecture, and material design using phonon-glass and electron-crystal concepts. The nanostructural approach helps to lower thermal conductivity but has limited effect on the power factor. Here, we demonstrate selective charge Anderson localization as a route to maximize the Seebeck coefficient while simultaneously preserving high electrical conductivity and lowering the lattice thermal conductivity.

Improving the zT value of thermoelectrics by nanostructuring: tuning the nanoparticle morphology of SbTe by using ionic liquids.

A systematic study on the microwave-assisted thermolysis of the single source precursor (EtSb)Te (1) in different asymmetric 1-alkyl-3-methylimidazolium- and symmetric 1,3-dialkylimidazolium-based ionic liquids (ILs) reveals the distinctive role of both the anion and the cation in tuning the morphology and microstructure of the resulting SbTe nanoparticles as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). A comparison of the electrical and thermal conductivities as well as the Seebeck coefficient of the SbTe nanoparticles obtained from different ILs reveals the strong influence of the specific IL, from which CmimI was identified as the best solvent, on the thermoelectric properties of as-prepared nanosized SbTe. This work provides design guidelines for ILs, which allow the synthesis of nanostructured thermoelectrics with improved performances.

Nanocrystalline silicon: lattice dynamics and enhanced thermoelectric properties.

Silicon has several advantages when compared to other thermoelectric materials, but until recently it was not used for thermoelectric applications due to its high thermal conductivity, 156 W K(-1) m(-1) at room temperature. Nanostructuration as means to decrease thermal transport through enhanced phonon scattering has been a subject of many studies. In this work we have evaluated the effects of nanostructuration on the lattice dynamics of bulk nanocrystalline doped silicon.