Transport Properties and Microstructure of Indium and Cerium added Cobalt-Antimony based Skutterudites

2011 ◽  
Vol 1329 ◽  
Author(s):  
A. Sesselmann ◽  
T. Dasgupta ◽  
C. Stiewe ◽  
E. Müller
Keyword(s):  
Transport Properties ◽  
Figure Of Merit ◽  
Temperature Dependent ◽  
Short Term ◽  
Cast Material ◽  
X Ray ◽  
Synthesis Parameters ◽  
Dimensionless Figure Of Merit ◽  
A Current ◽  
Scanning Electron

ABSTRACTIndium and cerium added cobalt-antimony based skutterudites with different filling fractions were synthesized using different annealing synthesis parameters. Phase homogeneity and microstructure of the resulting as-cast material were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The skutterudite material was further compacted using a current-assisted short-term sintering device. Temperature dependent measurements of the Seebeck coefficient, electrical and thermal conductivity were carried out on the compacted specimens in the temperature range of 350 K-700 K. Results indicate significant differences in the transport properties between the slowly cooled and quenched as‑cast materials and also with different filling fractions. Based on the measured transport properties the dimensionless figure of merit ZT was calculated for different filling fractions of indium and cerium. Among these compositions a ZTmax of 1.1 at 700 K was obtained.

scholarly journals Effect of Surfactant Addition on Bi2Te3 Nanostructures Synthesized by Hydrothermal Method

2017 ◽  
Vol 62 (2) ◽  
pp. 1005-1010 ◽  
Author(s):  
Peyala Dharmaiah ◽  
C.H. Lee ◽  
B. Madavali ◽  
Soon-Jik Hong
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Method ◽  
Figure Of Merit ◽  
Bulk Sample ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coarse Grains ◽  
Scanning Electron ◽  
Nanostructured Sample

AbstractIn the present work, we have prepared Bi2Te3nanostructures with different morphologies such as nano-spherical, nanoplates and nanoflakes obtained using various surfactant additions (EG, PVP, and EDTA) by a hydrothermal method. The shape of the nanoparticles can be controlled by addition of surfactants. The samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that the minority BiOCl phase disappears after maintained pH at 10 with EG as surfactant. SEM bulk microstructure reveals that the sample consists of fine and coarse grains. Temperature dependence of thermoelectric properties of the nanostructured bulk sample was investigated in the range of 300-450K. The presence of nanograins in the bulk sample exhibits a reduction of thermal conductivity and less effect on electrical conductivity. As a result, a figure of merit of the sintered bulk sample reached 0.2 at 400 K. A maximum micro Vickers hardness of 102 Hv was obtained for the nanostructured sample, which was higher than the other reported results.

scholarly journals Valorization of Brick and Glass CDWs for the Development of Geopolymers Containing More Than 80% of Wastes

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 672
Author(s):  
Dimitris Kioupis ◽  
Aggeliki Skaropoulou ◽  
Sotirios Tsivilis ◽  
Glikeria Kakali
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Circular Economy ◽  
X Ray Diffraction ◽  
Glass Waste ◽  
X Ray ◽  
Optimum Synthesis ◽  
Synthesis Parameters ◽  
Construction And Demolition Wastes ◽  
Scanning Electron

One of the areas of priority in a circular economy, regarding waste management, regards the valorization of construction and demolition wastes (CDW). This study suggests the synthesis of geopolymeric binders based almost entirely on construction and demolition wastes. Ceramic waste was used as the aluminosilicate precursor of the geopolymer synthesis, while glass waste was applied in the preparation of the activation solution. A fractional experimental design defined the optimum synthesis parameters, based on compressive strength values. The final products were characterized by means of X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The glass waste was appropriately processed in order to prepare the activation solution for the geopolymerization of brick waste. In this work, CDW-based geopolymers were produced with a compressive strength in the range 10–44 MPa. The developed products contained 80–90 wt.% CDWs, depending on the method of activator preparation.

Wear Studies on Aircraft Brake Materials

1978 ◽  
Vol 100 (1) ◽  
pp. 98-103 ◽  
Author(s):  
Ting Long Ho
Keyword(s):  
Chemical Element ◽  
Element Distribution ◽  
Wear Particles ◽  
Surface Cracks ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Surface Layers ◽  
Wear Model ◽  
X Ray ◽  
Scanning Electron

An investigation of both worn surfaces of friction pads and steel rotors which are being applied in current aircraft brakes has been carried out by employing an x-ray diffraction technique. It consists of the analysis of chemical element distribution in the surface layers. The wear particles were also examined by using the scanning electron microscope. The initiation and growth of surface cracks and the oxidation were emphasized in this investigation. A wear model was proposed for the current aircraft brake materials. Essentially this model proposed that cracks are formed in the surface layer of the break material due to the normal and fractional stresses. It is primarily surface temperature dependent.

scholarly journals Synthesis of Nanocrystalline Mg-Al Hydrotalcites in the Presence of Starch—the Effect on Structure and Composition

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 602
Author(s):  
Alicja Michalik ◽  
Bogna D. Napruszewska ◽  
Anna Walczyk ◽  
Joanna Kryściak-Czerwenka ◽  
Dorota Duraczyńska ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Parameters ◽  
All Solutions ◽  
Co Precipitation ◽  
Starch Potato ◽  
Degree Of Order ◽  
Scanning Electron

The study describes the synthesis of Mg-Al hydrotalcite (Ht) with the use of starch as a structure controlling biotemplate. Syntheses were carried out at room temperature, by co-precipitation at pH = 10. The investigated synthesis parameters included the nature of the precipitating agent (NaOH/Na2CO3 or NH3aq/(NH4)2CO3), the nature of starch (potato, corn and cassava), the method of starch addition to reagents, the method of drying and the effect of washing. The materials were examined with X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy and infrared spectroscopy. The data show that synthesis of Ht materials in the presence of starch, with use of the ammonia-based precipitant, enabled preparation of nanocrystalline Ht with very fine (<50 nm) particle size. All investigated starches had a similar effect on the crystallinity and the grain size of Ht precipitates. Ht with the smallest nanocrystals was obtained when starch was present in all solutions used for synthesis, and the final product subjected to freeze drying. Washing with water was found to enhance recrystallization and exchange of nitrates for carbonates. Infrared spectra showed that an interaction exists between the biopolymer template and the Ht particles, resulting in a higher degree of order within the Ht-adhering starch component.

Effect of Ni in new skutterudite compounds CaxCo4Sb12

2003 ◽  
Vol 793 ◽  
Author(s):  
Matthieu Puyet ◽  
Bertrand Lenoir ◽  
Anne Dauscher ◽  
Hubert Scherrer ◽  
Moukrane Dehmas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermal Properties ◽  
Beneficial Effect ◽  
Transport Properties ◽  
Figure Of Merit ◽  
Positive Influence ◽  
Temperature Range ◽  
Dimensionless Figure Of Merit ◽  
Ni Substitution

ABSTRACTThe transport properties of the partially filled CaxCo4-yNiySb12 skutterudite compounds have been investigated in the 300 – 800 K temperature range. We underline the positive influence of the Ni substitution on the electrical resistivity and thermopower while the thermal properties – thermal conductivity – remains almost unaffected. These results suggest again a beneficial effect of Ni atoms on the dimensionless figure of merit in CoSb3 based compounds.

Correlations Between Conditions of Synthesis, Phase Composition and Luminescent Properties of Eu - Polytantalate

2003 ◽  
Vol 796 ◽  
Author(s):  
Vladimir Vasilyev ◽  
Alvin Drehman ◽  
Lionel Bouthillette
Keyword(s):  
Phase Composition ◽  
Luminescent Properties ◽  
Luminescent Materials ◽  
Temperature Dependent ◽  
Sintered Ceramic ◽  
X Ray ◽  
Synthesis Conditions ◽  
Ceramic Thin Films ◽  
Synthesis Parameters ◽  
Temperature Dependent Photoluminescence

ABSTRACTCorrelations between synthesis conditions, phase composition, and spectral properties of the sintered ceramic, thin films and single crystals of EuTa7O19 phosphors have been studied using x-ray diffractometry and temperature dependent photoluminescence (PL) spectroscopy at temperatures between 18 K and 650 K. From the PL spectra of Eu3+, one can obtain information about the area of homogeneity of phases, their temperature transformations, and changes in the bonding character in the neighborhood of the luminescent ion. As a result, this information helps to optimize the synthesis parameters for luminescent materials.

Effect of Pr-Substitution in Eu1-xPrxBaSrCu3O7-δ on the Superconductivity and Transport Properties

2014 ◽  
Vol 895 ◽  
pp. 91-94
Author(s):  
Nor Azah Nik-Jaafar ◽  
Roslan Abd-Shukor ◽  
Wei Kong
Keyword(s):  
Electron Microscope ◽  
Critical Temperature ◽  
Transport Properties ◽  
Transport Critical Current Density ◽  
Pair Breaking ◽  
X Ray ◽  
Breaking Mechanism ◽  
Magnetic Pair ◽  
Scanning Electron ◽  
The Eu

The effect of Pr-substitution at the Eu-site on the superconductivity and transport properties in Eu1-xPrxBaSrCu3O7-d (x = 0.0, 0.1, 0.2, 0.4, 0.5) has been investigated. Tc onset for x = 0.0, 0.1, 0.2, 0.4, 0.5 are 86 K, 75 K, 65 K, 38 K, 27 K, respectively. The critical temperature (Tc) decreased linearly with increase in Pr concentration x indicating a magnetic pair-breaking mechanism. The transport critical current density (Jc) decreased with increasing x. Analysis of the structure of the samples via X-ray powder diffraction (XRD) technique showed transformation from orthorhombic to pseudo-tetragonal structure at x = 0.2. Scanning electron microscope (SEM) showed no variation in the microstructure.

High-Temperature Transport Properties of Indium Added Cobalt-Antimonide Based Skutterudites Processed by Current Assisted Short-Term Sintering

2010 ◽  
Vol 74 ◽  
pp. 54-59 ◽  
Author(s):  
Andreas Sesselmann ◽  
Ralf Hassdorf ◽  
Sebastian Zastrow ◽  
Eckhard Müller
Keyword(s):  
High Temperature ◽  
Bulk Material ◽  
Process Time ◽  
Material System ◽  
Short Term ◽  
X Ray ◽  
Functional Homogeneity ◽  
Cobalt Antimonide ◽  
Te Material ◽  
A Current

For more than a decade, skutterudites such as cobalt antimonides have been widely studied as a promising thermoelectric (TE) material for high-temperature applications. High thermoelectric figure of merit (ZT) in this material system can be achieved by suitable doping or by filling the interstitial voids with guest atoms. One of the best improvements in ZT is reported when indium (In) is used as additive to cobalt-antimonide skutterudites, as has been done in this study. Compaction of the grinded powders was carried out by a current-assisted short-term sintering device, which significantly reduces the process time in comparison to conventional hot pressing. Phase homogeneity of the bulk material has been probed by X-ray powder diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). TE properties (i.e. electrical conductivity, Seebeck coefficient and thermal conductivity) have been analyzed in the temperature range from 300 K to 700 K. The functional homogeneity of the samples was screened by the Potential & Seebeck Microprobe (PSM). Adapted from these results the effect of indium addition to short-term sintered cobalt-antimonide based skutterudites with absence of impurity phases will be discussed.

scholarly journals Bimetallic Co-Based (CoM, M = Mo, Fe, Mn) Coatings for High-Efficiency Water Splitting

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 92
Author(s):  
Jadranka Milikić ◽  
Aldona Balčiūnaitė ◽  
Zita Sukackienė ◽  
Dušan Mladenović ◽  
Diogo M. F. Santos ◽  
...  
Keyword(s):  
Current Density ◽  
Potassium Hydroxide ◽  
Electroless Deposition ◽  
High Efficiency ◽  
Low Cost ◽  
Copper Substrate ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Current ◽  
Scanning Electron

Bimetallic cobalt (Co)-based coatings were prepared by a facile, fast, and low-cost electroless deposition on a copper substrate (CoFe, CoMn, CoMo) and characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction analysis. Prepared coatings were thoroughly examined for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution (1 M potassium hydroxide, KOH) and their activity compared to that of Co and Ni coatings. All five coatings showed activity for both reactions, where CoMo and Co showed the highest activity for HER and OER, respectively. Namely, the highest HER current density was recorded at CoMo coating with low overpotential (61 mV) to reach a current density of 10 mA·cm−2. The highest OER current density was recorded at Co coating with a low Tafel slope of 60 mV·dec−1. Furthermore, these coatings proved to be stable under HER and OER polarization conditions.

Decreased Thermal Conductivity of CaMnO3 by Added-CNTs

2013 ◽  
Vol 770 ◽  
pp. 327-330
Author(s):  
Prapawan Thongsri ◽  
Tosawat Seetawan
Keyword(s):  
Thermal Conductivity ◽  
Manganese Oxide ◽  
Figure Of Merit ◽  
Solid State Reaction Method ◽  
Precursor Powder ◽  
Molar Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimensionless Figure Of Merit

The CaMnO3compound is synthesized by solid state reaction method. The precursor powder of calcium carbonate (CaCO3) and manganese oxide (MnO2) are mixed by ball milling then calcined at 850°C for 10 h and sintering at 1,150 °C for 36 h to obtain the calcium manganese oxide (CaMnO3) compound. The compound was doped the carbon nanotubes (CNTs) 2%, 4%, 6%, 8% and 10% by molar ratio following the calcinations and sintering process. The morphology and crystallography of the samples are analyzed by the X-ray diffraction (XRD) technique and scanning electron microscope (SEM). The Seebeck coefficient (S), electrical resistivity (ρ), thermal conductivity (κ) and dimensionless figure of merit were anlyzed. It results shown in a good thermoelectric properties after doping CNTs.

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