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155 results on '"Gelbstein, Yaniv"'

12. Influence of the La 0.2 Sr 0.7 Ti 0.95 Ni 0.05 O 3 (LSTN) Synthesis Method on SOFC Anode Performance.

Author

Dahan, Moran, Fadeev, Ludmila, Hayun, Hagay, Gozin, Michael, Gelbstein, Yaniv, and Rosen, Brian A.

Subjects
STRONTIUM titanate, SOLID oxide fuel cells, FUEL cells, ANODES, CHEMICAL energy, X-ray diffraction
Abstract

Solid oxide fuel cells are characterized by a high efficiency for converting chemical energy into electricity and fuel flexibility. This research work focuses on developing durable and efficient anodes for solid oxide fuel cells (SOFCs) based on exsolving nickel from the perovskite structure. A-site-deficient La- and Ni-doped strontium titanates (La0.2Sr0.7Ti0.95Ni0.05O3−δ, LSTN) were synthesized using four different techniques and mixed with Ce0.8Gd0.2O2−δ (GDC) to form the SOFC anode. The synthesis routes of interest for comparison included solid-state, sol-gel, hydrothermal, and co-precipitation methods. LSTN powders were characterized via XRD, SEM, TPR, BET and XPS. In situ XRD during reduction was measured and the reduced powders were analyzed using TEM. The impact of synthesis route on SOFC performance was investigated. All samples were highly durable when kept at 0.5 V for 48 h at 800 °C with H2 fuel. Interestingly, the best performance was observed for the cell with the LSTN anode prepared via co-precipitation, while the conventional solid-state synthesis method only achieved the second-best results. [ABSTRACT FROM AUTHOR]

Published
2024
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25. High-ZT Due to the Influence of Copper in Ti(Ni 1- x Cu x)Sn.

Author

Sadia, Yatir, Lumbroso, Dan, and Gelbstein, Yaniv

Subjects
COPPER, THERMOELECTRIC materials, HOT pressing, X-ray diffraction, THERMAL conductivity, COPPER-titanium alloys, COPPER-tin alloys
Abstract

Most high-performance thermoelectric materials require either expensive, rare, or toxic elements. By doping TiNiSn, a low-cost, abundant thermoelectric compound, with copper as an n-type donor, some optimization can be performed for such materials. Ti(Ni1-xCux)Sn was synthesized by arc melting followed by heat treatment and hot pressing. The resulting material was analyzed for its phases using XRD and SEM and its transport properties. Cu undoped and 0.05/0.1% doped samples showed no additional phases in addition to the matrix half-Heusler phase, while the 1% copper doping initiated some Ti6Sn5 and Ti5Sn3 precipitation. The transport properties showed that copper acts as an n-type donor while also lowing the lattice thermal conductivity of the materials. the sample containing 0.1% copper showed the best figure of merit, ZT, with a maximal value of 0.75 and an average value of 0.5 through 325–750 K showing a 125% improvement over the undoped sample of TiNiSn. [ABSTRACT FROM AUTHOR]

Published
2023
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41. The Initial Stage in Oxidation of ZrNiSn (Half Heusler) Alloy by Oxygen

Author

Appel, Oshrat, Breuer, Gil, Cohen, Shai, Beeri, Ofer, Kyratsi, Theodora, Gelbstein, Yaniv, Zalkind, Shimon, and Kyratsi, Theodora [0000-0003-2916-1708]

Subjects
Materials science, surface oxidation, Alloy, Oxide, chemistry.chemical_element, engineering.material, thermoelectric, Oxygen, lcsh:Technology, Article, chemistry.chemical_compound, X-ray photoelectron spectroscopy, Thermoelectric effect, half-Heusler, XPS, General Materials Science, lcsh:Microscopy, lcsh:QC120-168.85, Zirconium, ZrNiSn, lcsh:QH201-278.5, lcsh:T, technology, industry, and agriculture, Thermoelectric materials, equipment and supplies, segregation, Surface energy, chemistry, Chemical engineering, lcsh:TA1-2040, engineering, lcsh:Descriptive and experimental mechanics, lcsh:Electrical engineering. Electronics. Nuclear engineering, lcsh:Engineering (General). Civil engineering (General), oxygen, lcsh:TK1-9971
Abstract

The MNiSn (M = Ti, Zr, Hf), half-Heusler semiconducting alloys have a high potential for use as n-type thermoelectric materials at elevated temperatures (~1000 K). The alloys&rsquo, durability is crucial for their commercial handling and use, and therefore it is required to characterize their surface oxidation behavior and stability at the working temperature. X-ray photoelectron spectroscopy was utilized to study the surface composition and oxidation of the ZrNiSn alloy at room and elevated temperatures. It was found that during heating in a vacuum, Sn segregates to the surface in order to reduce the surface energy. Exposing the alloy to oxygen resulted mainly in the oxidation of the zirconium to ZrO2, as well as some minor oxidation of Sn. At room temperature, the oxidation to ZrO2 was accompanied by the formation of a thin ZrO layer at the metal-oxide interface. In contrast to TiNiSn, where most of the oxide was formed on the surface due to oxygen-enhanced segregation of Ti, and in the case of ZrNiSn, the formed oxide layer was thinner. Part of the oxide is formed due to Zr segregation to the surface, and in part due to oxygen dissolved into the alloy.

Published
2019

49. Simulation of Morphological Effects on Thermoelectric Power, Thermal and Electrical Conductivity in Multi‐Phase Thermoelectric Materials

Author

Gelbstein, Yaniv

Subjects
Technology & Engineering / Electrical
Abstract

Multi‐phase thermoelectric materials are mainly investigated these days due to their potential of lattice thermal conductivity reduction by scattering of phonons at interfaces of the involved phases, leading to the enhancement of expected thermoelectric efficiency. On the other hand, electronic effects of the involved phases on thermoelectric performance are not always being considered, while developing new multi‐phase thermoelectric materials. In this chapter, electronic effects resulting from controlling the phase distribution and morphology alignment in multi‐phase composite materials is carefully described using the general effective media (GEM) method and analytic approaches. It is shown that taking into account the specific thermoelectric properties of the involved phases might be utilized for estimating expected effective thermoelectric properties of such composite materials for any distribution and relative amount of the phases. An implementation of GEM method for the IV–VI (including SnTe and GeTe), bismuth telluride (Bi2Te3), higher manganese silicides (HMS) and half‐Heusler classes of thermoelectric materials is described in details.

Published
2016

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