Crystal Structure and Thermoelectric Properties of Novel Quaternary CuMHfS (M-Mn, Fe, Co, and Ni) Thiospinels with Low Thermal Conductivity.

Uncovering of the origin of intrinsically low thermal conductivity in novel crystalline solids is among the main streams in modern thermoelectricity. Because of their earth-abundant nature and environmentally friendly content, Cu-based thiospinels are attractive functional semiconductors, including thermoelectric (TE) materials. Herein, we report the crystal structure, as well as electronic and TE properties of four new CuMHfS (M-Mn, Fe, Co, and Ni) thiospinels.

Phase Analysis and Thermoelectric Properties of Cu-Rich Tetrahedrite Prepared by Solvothermal Synthesis.

Because of the large Seebeck coefficient, low thermal conductivity, and earth-abundant nature of components, tetrahedrites are promising thermoelectric materials. DFT calculations reveal that the additional copper atoms in Cu-rich CuSbS tetrahedrite can effectively engineer the chemical potential towards high thermoelectric performance. Here, the Cu-rich tetrahedrite phase was prepared using a novel approach, which is based on the solvothermal method and piperazine serving both as solvent and reagent.

Entropy-Induced Multivalley Band Structures Improve Thermoelectric Performance in -CuP(SSe) Argyrodites.

Searching for novel low-cost and eco-friendly materials for energy conversion is a good way to provide widespread utilization of thermoelectric technologies. Herein, we report the thermal behavior, phase equilibria data, and thermoelectric properties for the promising argyrodite-based CuP(SSe) thermoelectrics. Alloying of CuPSe with CuPS provides a continuous solid solution over the whole compositional range, as shown in the proposed phase diagram for the CuPS-CuPSe system.

Thermoelectric properties of the tetrahedrite-tennantite solid solutions CuSbAsS and CuCoSbAsS (0 ≤ x, y ≤ 4).

Tetrahedrites, a class of copper- and sulfur-rich minerals, exhibit inherently very low lattice thermal conductivity and adjustable electronic properties that make them interesting candidates for thermoelectric applications. Here, we investigate the influence of isovalent As substitution on the Sb site on the structural and transport properties (5-700 K) of the two solid solutions Cu12Sb4-xAsxS13 and Cu10Co2Sb4-yAsyS13 (0 ≤ x, y ≤ 4). Electronic band structure calculations predict that As has only a weak influence on the valence bands and hence, on the p-type metallic character of Cu12Sb4S13.

An Sn-induced resonant level in β-AsTe.

Distortion of the density of states by an impurity-induced resonant level has been shown to provide an effective strategy to improve the thermoelectric performance of semiconductors such as Bi2Te3, PbTe or SnTe. Here, combining first-principles calculations and transport property measurements, we demonstrate that Sn is a resonant impurity that distorts the valence band edge in p-type β-As2Te3. This remarkable effect is characterized as a prominent, sharp peak in the electronic density of states near the Fermi level.

Correlation between electronic structure, transport and electrochemical properties of a LiNiCoMnO cathode material.

Herein, the correlation between electronic structure, transport and electrochemical properties of layered LiNiCoMnO cathode material is revealed. Comprehensive experimental studies of physicochemical properties of LiNiCoMnO cathode material (XRD, electrical conductivity, thermoelectric power) are supported by electronic structure calculations performed using the Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA) to account for the chemical disorder. It is found that even small O defects (∼1%) could significantly modify electronic density of states DOS characteristics via the formation of extra broad peaks inside the former band gap leading to its substantial narrowing.

Effect of Isovalent Substitution on the Electronic Structure and Thermoelectric Properties of the Solid Solution α-AsTeSe (0 ≤ x ≤ 1.5).

We report on the influence of Se substitution on the electronic band structure and thermoelectric properties (5-523 K) of the solid solution α-AsTeSe (0 ≤ x ≤ 1.5). All of the polycrystalline compounds α-AsTeSe crystallize isostructurally in the monoclinic space group C2/m (No.

Anomaly in the electronic structure of the Na(x)CoO(2-y) cathode as a source of its step-like discharge curve.

In this paper we would like to show a new approach to an explanation of the nature of the discharge-charge curve of Na/Na(+)/NaxCoO2-y batteries, which can justify the existence of the step-like characteristics. This is still an open problem, which until now had no proper description in the literature. On the basis of comprehensive experimental studies of physicochemical properties of NaxCoO2-y cathode material (XRD, electrical conductivity, thermoelectric power, electronic specific heat) supported by calculations performed using the DFT method with accounting for chemical disorder, it has been shown that the observed step-like character of the discharge curve reflects the variation of the chemical potential of electrons (Fermi level) in the density of states of NaxCoO2-y, which is anomalously perturbed by the presence of the oxygen vacancy defects and sodium ordering.

Neutron diffraction, electronic band structure, and electrical resistivity of Mo(3-x)Ru(x)Sb(7).

Neutron diffraction experiments and Korringa-Kohn-Rostoker with coherent potential approximation electronic band structure calculations as well as electrical resistivity measurements have been performed on polycrystalline Mo(3-x)Ru(x)Sb(7) samples for 0 < or = x < or = 1. Neutron diffraction studies have been undertaken at room temperature and extended down to 4 K to get a better understanding of the crystalline structure modifications as the Ru content increases. Both structural and chemical characterizations have unambiguously revealed a solubility limit of the Ru atoms close to 0.