Nickel bis­muth boride, Ni23-xBixB6 [x = 2.44 (1)]

The τ-boride Ni23-xBixB6 [x = 2.44 (1)] adopts a ternary variant of the cubic Cr23C6-type structure, with Ni8 cubes and Ni12 cubocta­hedra arranged in a NaCl-type pattern. Two of the four independent metal sites (8c, 3m symmetry; 4a, m m symmetry) are occupied by a mixture of Ni and Bi atoms in a 0.106 (6):0.894 (6) and a 0.350 (7):0.650 (7) ratio, respectively

Thermoelectric Higher Manganese Silicide: Synthetized, sintered and shaped simultaneously by selective laser sintering/Melting additive manufacturing technique

Complex geometry legs were advantageous to obtain higher thermoelectric potential due to a better thermal dissipation. Among all industrial processes, additive manufacturing using a selective laser sintering (SLS) or melting (SLM) techniques is the most promising to obtain such complex-shape legs without machining step. In this work, for the first time, Higher Manganese Silicide (HMS) sheet samples were synthetized, sintered and shaped simultaneously by additive manufacturing from ball milled manganese and silicon powder. Impact of surface power density and scanning rate of the laser on the microstructural and structural properties was discussed for some SLS/M parameters. Characterizations have shown that both densification and pure HMS phase can be obtained by SLS/M

Isothermal section of the ternary phase diagram U–Fe–Ge at 900 °C and its new intermetallic phases

International audienc

Examples of Studies on Electrophoretic Deposition Process of Functional Thin Films

Please click Additional Files below to see the full abstract

Stability and thermoelectric performance of doped higher manganese silicide materials solidi fied by RGS (ribbon growth on substrate) synthesis

Large scale deployment of thermoelectric devices requires that the thermoelectric materials have stable electrical, thermal and mechanical properties under the conditions of operation. In this study we examine the high temperature stability of higher manganese silicide (HMS) materials prepared by the RGS (ribbon growth on substrate) technique. In particular we characterize the effect of element substitution on the structural and electrical changes occurring at the hot side of temperatures of thermoelectric devices relevant to this material (600°C). Only by using suitable substitution (4% vanadium at the Mn site) can we obtain temperature-independent structural parameters in the range 20°C - 600°C, a condition that results in stable electrical properties. Additionally, we show that 4% vanadium substitution at the Mn site offers the best thermoelectric figure of merit among the different compositions reported here with ZTmax=0.52, a value comparable to the state of the art for HMS materials. Our analysis suggests that ionized impurity scattering is responsible for the better performance of this material

Effect of Nanostructuring on the Thermoelectric Properties of β-FeSi2

Nanostructured β-FeSi2 and β-Fe0.95Co0.05Si2 specimens with a relative density of up to 95% were synthesized by combining a top-down approach and spark plasma sintering. The thermoelectric properties of a 50 nm crystallite size β-FeSi2 sample were compared to those of an annealed one, and for the former a strong decrease in lattice thermal conductivity and an upshift of the maximum Seebeck’s coefficient were shown, resulting in an improvement of the figure of merit by a factor of 1.7 at 670 K. For β-Fe0.95Co0.05Si2, one observes that the figure of merit is increased by a factor of 1.2 at 723 K between long time annealed and nanostructured samples mainly due to an increase in the phonon scattering and an increase in the point defects. This results in both a decrease in the thermal conductivity to 3.95 W/mK at 330 K and an increase in the power factor to 0.63 mW/mK2 at 723 K

Robust, Transparent Hybrid Thin Films of Phase-Change Material Sb2S3 Prepared by Electrophoretic Deposition

Thin films of polyethylenimine-stabilized Sb2S3 are prepared via electrophoretic deposition (EPD), showing strong adhesion between the deposited layers and the underlying substrate, with the films being crystallized via annealing. For amorphous films, thicknesses can be freely tuned from 0.2 to 1 μm, shrinking to 0.1–0.5 μm when crystallized, while retaining a crack- and defect-free surface, thus not impacting their good stability and maintaining their optical properties. Through UV–vis spectroscopy and subsequent modeling of the obtained spectra, it was concluded that the materials after annealing showed a reduced band gap and a demonstrably increased refractive index (n) and carrier concentration. The use of EPD for this material shows the viability of rapidly creating stable thin films of phase-change materials

Roadmap on energy harvesting materials

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere

Suppression of superconductivity and resistivity anomaly in Rh17S15 by cobalt substitution

The chalcogenide superconductor Rh17S15 is known for having an upper critical field of nearly twice the Pauli limit and an unusual temperature dependence of the resistivity. When doped with small amounts of cobalt, superconductivity in Rh17-xCoxS15 (0 < x < 3) is systematically suppressed. We explore the evolution of the electrical transport properties from 2-300 K as a function of x. We identify three temperature regimes which are differently affected by doping. The disappearance of an electron-like contribution to the transport at low temperature is correlated with the suppression of superconductivity

Thermoelectric properties of n-type cobalt doped chalcopyrite Cu1−xCoxFeS2 and p-type eskebornite CuFeSe2

International audienceChalcopyrite CuFeS2 has been recently suggested as a promising thermoelectric material. In the present paper, the transport properties – electrical resistivity ρ and Seebeck coefficient S – of the n-type CuFeS2 chalcopyrite and the p-type CuFeSe2 eskebornite have been measured. Very different groundstates are evidenced with a semimetallic behavior concomitant to a metal-like S(T) curve for CuFeSe2 whereas CuFeS2 is a semiconductor with much larger |S| values. For that reason, charge creation by Co2+ for Cu+ substitution in CuFeS2 has been performed. The veracity of the Co for Cu substitution for x ≤ 0.10 in Cu1−xCoxFeS2 chalcopyrite has been confirmed by EDS analyses, coupled to electron diffraction, with a transmission electron microscope. Also, this study demonstrates the existence of twinning domains. The compounds corresponding to the best compositions in terms of power factor have been densified by Spark Plasma Sintering for thermal conductivity measurements. A maximum ZT value up to 0.22 at 675 K for Cu0.96Co0.04FeS2 has been obtained. © 2015 The Author