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1. The Synthesis and Thermoelectric Properties of the n-Type Solid Solution Bi2−xSbxTe3 (x < 1)

Author

Amélie Galodé, Tristan Barbier, and Franck Gascoin

Subjects
Bi2Te3, Bi2−xSbxTe3, n-type, thermoelectric, mechanical alloying, SPS, Technology, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Engineering (General). Civil engineering (General), TA1-2040, Microscopy, QH201-278.5, Descriptive and experimental mechanics, QC120-168.85
Abstract

Commercial Peltier cooling devices and thermoelectric generators mostly use bismuth telluride-based materials, specifically its alloys with Sb2Te3 for the p-type legs and its alloys with Bi2Se3 for the n-type legs. If the p-type materials perform with zT well above the unity around room temperature, the n-type counterpart is lacking efficiency in this temperature range, and has the disadvantage of containing selenium. Indeed, despite the fact that selenium is not environmentally benign and that its handling requires precautions, the use of selenium does not facilitate the optimization of thermoelectric performance at or around room temperature, as the presence of selenium results in a larger band gap. In this study, we investigate the feasibility of a selenium-free n-type (Bi, Sb)2Te3 using a simple two-step process: mechanical alloying synthesis followed by spark plasma sintering. All the members of the solid solution Bi2−xSbxTe3 with x < 1 are n-type materials, with zTs between 0.35 and 0.6. The zT is maximized at lower temperatures with an increasing Sb content, which is proof that the band gap is reduced accordingly. We also show here that an edge-free sintering process considerably improves thermoelectric performance.

Published
2023
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2. Structural study and evaluation of thermoelectric properties of single-phase isocubanite (CuFe2S3) synthesized via an ultra-fast efficient microwave radiation technique

Author

Volker Eyert, Rodolphe Macaigne, Antoine Maignan, Bhuvanesh Srinivasan, Oleg I. Lebedev, Tristan Barbier, David Berthebaud, Sylvain Marinel, Emmanuel Guilmeau, Raymond Frésard, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Diffraction, chemistry.chemical_classification, Condensed Matter - Materials Science, Materials science, Sulfide, Renewable Energy, Sustainability and the Environment, Energy Engineering and Power Technology, chemistry.chemical_element, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Nanotechnology, Thermoelectric materials, Copper, Fuel Technology, chemistry, Phase (matter), Thermoelectric effect, [CHIM]Chemical Sciences, Ultra fast, Microwave
Abstract

The current state-of-the-art thermoelectric materials are generally composed of expensive, scarce, and toxic elements. In this respect, copper-based sulfide compounds have emerged as viable alternatives. Herein, we report for the first time the successful synthesis of single-phase cubic isocubanite CuFe2S3 using mechanical-alloying combined with microwave-assisted synthesis. The isocubanite phase synthesized via this ultra-fast out-of-equilibrium process exhibits a maximum thermoelectric figure of merit, zTmax ~ 0.14 at 673 K. Besides the thermoelectric properties, insights about the structure of isocubanite, based on the refinement of X-ray diffraction data and first principles calculations, are also investigated in detail. It confirms that the Cu-Fe cations in synthetic isocubanite overwhelmingly occupy the 4d sites of the cubic structure in an inherently disordered fashion., 18 pages, 7 figures

Published
2022

3. Na 2 VO(HPO 4 ) 2 : an original phase solved by continuous 3D electron diffraction and powder X-ray diffraction

Author

V. Gopal, Valerie Pralong, O. Leynaud, M. Gnanavel, C. Lepoittevin, Tristan Barbier, A. Neveu, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Matériaux, Rayonnements, Structure (MRS), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), X'Press (X'Press), and Normandie Université (NU)

Subjects
Diffraction, Materials science, Proton, Cathode material, Analytical chemistry, 02 engineering and technology, Crystal structure, 010402 general chemistry, 01 natural sciences, Ion, Inorganic Chemistry, Phase (matter), [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM]Chemical Sciences, 3D Electron Diffraction, Na2VO(HPO4)2, exchange, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Electron diffraction, X-ray crystallography, Vanadium hydrogeno phosphate, Transmission Electron Microscopy, Orthorhombic crystal system, 0210 nano-technology, Na-ion battery
Abstract

International audience; The new phase Na 2 VO(HPO 4) 2 was synthesized by sodium/proton ion exchange between NaI and VO (H 2 PO 4) 2 in hexanol. The exchange of two protons by two sodium ions causes a structural reorganization leading to a new original phase. The crystal structure was solved by continuous 3D Electron Diffraction, consisting of recording a video in diffraction mode during the continuous sample holder rotation in order to acquire a complete dataset in a shortest time in order to avoid the deterioration of this electron beam sensitive material. The individual Electron Diffraction patterns were extracted from the video, processed by conventional electron diffraction crystallography programs (PETS, JANA2006) and the resulting structural model calculated by the charge flipping algorithm was refined from powder X-ray diffraction data. This material crystallizes in an orthorhombic unit cell in the Iba2 (45) space group, with the cell parameters a = 13.86852(19), b = 13.7985(2), c = 7.47677(9). Electrochemical studies show that up to 0.66 Na f.u. −1 could be removed from Na 2 VO(HPO 4) 2 .

Published
2021

4. Tetrahedrites Synthesized via Scalable Mechanochemical Process and Spark Plasma Sintering

Author

Tristan Barbier, Matej Baláž, Mária Kaňuchová, Oleksandr Dobrozhan, Peter Baláž, Emmanuel Guilmeau, Marcela Achimovičová, Nina Daneu, Jaroslav Briančin, Michal Hegedüs, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Slovak Academy of Sciences (SAS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Jozef Stefan Institute [Ljubljana] (IJS), Sumy State University, Synthon, and Technical University of Kosice

Subjects
Mechanochemical, Materials science, Tetrahedrite, Sulfide, Composite number, Spark plasma sintering, SPS, 02 engineering and technology, engineering.material, 01 natural sciences, Thermal conductivity, 0103 physical sciences, Thermoelectric effect, Materials Chemistry, 010302 applied physics, Thermoelectric, [CHIM.MATE]Chemical Sciences/Material chemistry, Covellite, 021001 nanoscience & nanotechnology, Thermoelectric materials, Chemical engineering, visual_art, Ceramics and Composites, visual_art.visual_art_medium, engineering, 0210 nano-technology, Ternary operation
Abstract

International audience; In this study, we demonstrate the use of elemental precursors (Cu,Sb,S) to synthesize tetrahedrite Cu12Sb4S13 using an industrial eccentric vibratory mill. Mechanochemical synthesis of tetrahedrite leads to the formation of covellite (CuS), skinnerite (Cu3SbS3) or famatinite (Cu3SbS4) in dependence on milling time. However, the composite product can be modified in favour of prevailing tetrahedrite when Spark Plasma Sintering (SPS) treatment is applied after milling. The as-synthesized and sintered products are composed of polydisperse nanosized particles with dimensions up to 250 nm. The thermoelectric measurements reveal a maximum value of figure-of-merit ZT = 0.67 @ 700 K, as a consequence of a relatively high power factor (1.07 mW m−1 K−2) and a low thermal conductivity (1.12 W m−1 K−1). The obtained zT values of products prepared in an industrial mill are comparable to the ones reported for compounds synthesized using laboratory mills. The synthesis of ternary and quaternary sulphides by a scalable and industrializable milling process represents a prospective route for mass production of thermoelectric materials.

Published
2020

5. XBi 4 S 7 (X = Mn, Fe): New Cost‐Efficient Layered n ‐Type Thermoelectric Sulfides with Ultralow Thermal Conductivity

Author

Héloïse Willeman, Pierric Lemoine, Erik Elkaim, Thierry Le Mercier, Carmelo Prestipino, Abdelhamid Bourhim, Florian Appert, Arthur Huguenot, Bernard Malaman, Régis Gautier, Jean Juraszek, Agathe Virfeu, Antoine Maignan, Rabih Al Rahal Al Orabi, Lauriane Pautrot-d'Alençon, Emmanuel Guilmeau, Tristan Barbier, Vivian Nassif, Jean-Baptiste Labégorre, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Solvay (France), Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), CRG et Grands Instruments (CRG ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), CRG & Grands instruments (NEEL - CRG), and Central Michigan University (CMU)

Subjects
Materials science, Condensed matter physics, Phonon, sulfides, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, thermoelectric, DFT calculations, 01 natural sciences, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, Biomaterials, Thermal conductivity, Thermoelectric effect, Electrochemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM]Chemical Sciences, thermal conductivity, 0210 nano-technology, phonon
Abstract

International audience; A new class of cost‐efficient n‐type thermoelectric sulfides with a layered structure is reported, namely MnBi4S7 and FeBi4S7. Theoretical calculations combined with synchrotron X‐ray/neutron diffraction analyses reveal the origin of their electronic and thermal properties. The complex low‐symmetry monoclinic crystal structure generates an electronic band structure with a mixture of heavy and light bands near the conduction band edge, as well as vibrational properties favorable for high thermoelectric performance. The low thermal conductivity can be attributed to the complex layered crystal structure and to the existence of the lone pair of electrons in Bi3+. This feature combined with the relatively high power factor lead to a figure of merit as high as 0.21 (700 K) in undoped MnBi4S7, making this material a promising n‐type candidate for low‐ and intermediate‐temperature thermoelectric applications.

Published
2019

6. CuFe2S3 as electrode material for Li-ion batteries

Author

Emmanuel Anger, Tristan Barbier, Valerie Pralong, Antoine Maignan, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)-Institut de Chimie du CNRS (INC)

Subjects
Electrode material, Materials science, General Chemical Engineering, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Electrochemistry, 01 natural sciences, 7. Clean energy, Copper, 0104 chemical sciences, Ion, [SPI.MAT]Engineering Sciences [physics]/Materials, chemistry, Chemical engineering, 0210 nano-technology
Abstract

International audience; Electrochemical performances of the isocubanite CuFe2S3 tested as electrode material for Li-ion batteries have been investigated. A first discharge capacity of 860 mA h g(-1) shows a conversion process leading to Li2S, copper and iron nanoparticles. Interestingly, a reversible capacity of 560 mA h g(-1) at 1.5 V is demonstrated with good cyclability up to 30 cycles.

Published
2018

7. The Influence of Mobile Copper Ions on the Glass-Like Thermal Conductivity of Copper-Rich Tetrahedrites

Author

Paz Vaqueiro, Anthony V. Powell, Tristan Barbier, Emmanuel Guilmeau, Gabin Guélou, Ronald I. Smith, Andreas Kaltzoglou, ISIS Facility, STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC)-Science and Technology Facilities Council (STFC), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), University of Reading (UOR), European Commission [315019], Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, General Chemical Engineering, Neutron diffraction, Analytical chemistry, Mineralogy, chemistry.chemical_element, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, Thermal conductivity, Phase (matter), Thermoelectric effect, Materials Chemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM]Chemical Sciences, Tetrahedrite, Lattices, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Thermoelectric materials, Copper, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Hysteresis, chemistry, Phase transitions, Temperature dependence, engineering, 0210 nano-technology
Abstract

International audience; Tetrahedrites are promising p-type thermoelectric materials for energy recovery. We present here the first investigation of the structure and thermoelectric properties of copper-rich tetrahedrites, Cu12+xSb4S13 (0 < x 0 consist of two tetrahedrite phases. In situ neutron diffraction data demonstrate that on heating, the two tetrahedrite phases coalesce into a single tetrahedrite phase at temperatures between 493 and 553 K and that this transition shows marked hysteresis on cooling. Our structural data indicate that copper ions become mobile above 393 K. Marked changes in the temperature dependence of the electrical and thermal transport properties of the copper-rich phases occur at the onset of copper mobility. Excess copper leads to a significant reduction in the total thermal conductivity, which for the nominal composition Cu14Sb4S13 reaches a value as low as 0.44 W m(-1) K-1 at room temperature, and to thermoelectric properties consistent with phonon liquid electron crystal (PLEC) behavior.

Published
2017

8. Copper Hyper-Stoichiometry: The Key for the Optimization of Thermoelectric Properties in Stannoidite Cu8+xFe3–xSn2S12

Author

Gerard Le Caër, Pierric Lemoine, Ventrapati Pavan Kumar, Bernard Malaman, Bernard Raveau, Tristan Barbier, Emmanuel Guilmeau, Ramzy Daou, Vincent Caignaert, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-09-01, Agence Nationale de la Recherche, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)

Subjects
Materials science, Analytical chemistry, chemistry.chemical_element, Spark plasma sintering, 02 engineering and technology, Stannite, engineering.material, Sulfides, 010402 general chemistry, 01 natural sciences, Thermal conductivity, Seebeck coefficient, Thermoelectric effect, Physical and Theoretical Chemistry, Thermoelectrics, Metallurgy, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Copper, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, General Energy, chemistry, engineering, Thermoelectric materials, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Tin, Stoichiometry
Abstract

International audience; A univalent copper hyper-stoichiometric stannoidite Cu8+xFe3–xSn2S12 with 0 ≤ x ≤ 0.5 has been synthesized using mechanical alloying followed by spark plasma sintering. The X-ray diffraction analysis combined with 57Fe and 119Sn Mössbauer investigations has allowed the charge distribution of the cationic species on the various sites to be established and suggests the possibility of a small tin deficiency. The transport properties show a remarkable crossover from a semiconducting to a metal-like behavior as the copper content increases from x = 0 to x = 0.5, whereas correlatively the Seebeck coefficient decreases moderately, with S values ranging from 310 to 100 μV/K. The thermal conductivity decreases as the temperature increases showing low values at high temperature, far below those reported in related stannite materials. The investigation of the thermoelectric properties shows that the ZT figure of merit is dramatically enhanced by the copper hyper-stoichiometry by a factor of 5 going from 0.07 for x = 0 to 0.35 for x = 0.5 at 630 K. This thermoelectric behavior is interpreted on the basis of a model involving the Cu–S framework as the conducting electronic network where the Fe2+/Fe3+ species play the role of hole reservoir.

Published
2017

9. Decreased thermal conductivity in Bi2Sr2Co2Ox bulk materials prepared by partial melting

Author

Robert Freer, Feridoon Azough, Tristan Barbier, Ryoji Funahashi, and Emmanuel Combe

Subjects
010302 applied physics, Materials science, Phonon scattering, Mechanical Engineering, Partial melting, Oxide, Analytical chemistry, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Hot pressing, Microstructure, 01 natural sciences, chemistry.chemical_compound, Thermal conductivity, chemistry, Mechanics of Materials, 0103 physical sciences, Thermoelectric effect, General Materials Science, 0210 nano-technology, Porosity
Abstract

Bi2Sr2Co2Ox (BSC-222) bulk materials have been prepared in air by single hot pressing or partial melting followed by hot pressing. Thermal transport properties of as-prepared samples were compared with BSC-222 samples prepared by single partial melting. Samples prepared through hot pressing have a high bulk density and improved preferential grain orientation. Bulk density andpreferential grain orientation are significantly better in samples processed by partial melting followed by hot pressing. In samples prepared by partial melting, the presence of sub-micrometer-sized secondary phases Bi0.75Sr0.25Ox, Sr-based oxide, and CoO, is observed. The lattice contribution to the total thermal conductivity decreases significantly in partially melted BSC-222 samples. By using a classical phonon transport model, this result demonstrates that the decrease in lattice thermal conductivity in partially melted BSC-222 samples may be linked not only to porosity but also to the presence of defects, induced by partial melting process, which may play an important role in phononscattering.

Published
2016

10. Thermoelectric properties of TiS2 mechanically alloyed compounds

Author

Nicolas Barrier, Anthony V. Powell, Emmanuel Guilmeau, Cédric Bourgès, Tristan Barbier, Gabin Guélou, Yoshiaki Kinemuchi, Paz Vaqueiro, Oleg I. Lebedev, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), University of Reading (UOR), National Institute of Advanced Industrial Science and Technology (AIST), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Electron mobility, Materials science, Niobium, Analytical chemistry, chemistry.chemical_element, Spark plasma sintering, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Thermoelectric effect, Materials Chemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM]Chemical Sciences, High-resolution transmission electron microscopy, Thermoelectric, Metallurgy, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Grain size, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Titanium disulfide, chemistry, Ceramics and Composites, Grain boundary, Crystallite, Mechanical alloying, 0210 nano-technology
Abstract

International audience; Bulk polycrystalline samples in the series Ti1-xNbxS2 (0 ≤ x ≤ 0.075) were prepared using mechanical alloying synthesis and spark plasma sintering. X-ray diffraction analysis coupled with high resolution transmission electron microscopy indicates the formation of trigonal TiS2 by high energy ball-milling. The as-synthesized particles consist of pseudo-ordered TiS2 domains of around 20-50 nm, joined by bent atomic planes. This bottom-up approach leads, after spark plasma sintering, to homogeneous solid solutions, with a niobium solubility limit of x = 0.075. Microstructural observations evidence the formation of small crystallites in the bulk compounds with a high density of stacking faults. The large grain boundary concentration coupled with the presence of planar defects, leads to a substantial decrease in the thermal conductivity to 1.8 W/mK at 700 K. This enables the figure of merit to reach ZT = 0.3 at 700 K for x = 0.05, despite the lower electron mobility in mechanically alloyed samples due to small crystallite/grain size and structural defects. © 2015 Elsevier Ltd.

Published
2016

11. The impact of charge transfer and structural disorder on the thermoelectric properties of cobalt intercalated TiS2

Author

Gabin Guélou, Paz Vaqueiro, Jesús Prado-Gonjal, Anthony V. Powell, Winfried Kockelmann, Tristan Barbier, Emmanuel Guilmeau, Sylvie Hébert, University of Reading (UOR), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Science and Technology Facilities Council (STFC), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)-Institut de Chimie du CNRS (INC)

Subjects
Materials science, Neutron diffraction, Thermoelectric equipment, chemistry.chemical_element, 02 engineering and technology, Charge carriers, Thermal transport properties, 010402 general chemistry, 01 natural sciences, Electrically conductive, Thermal conductivity, Charge transfer, Electric conductivity, Van der Waals forces, Concomitant reduction, Thermoelectric performance, Electrical resistivity and conductivity, Vacancy defect, Thermoelectric effect, Materials Chemistry, Electrical conductivity, [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM]Chemical Sciences, Thermal analysis, General Chemistry, Cobalt, Thermoanalysis, Thermoelectricity, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Crystallography, chemistry, Thermoelectric properties, Transport properties, Charge carrier, Carrier concentration, Powder neutron diffraction, 0210 nano-technology, Lattice contribution
Abstract

International audience; A family of phases, CoxTiS2 (0 ≤ x ≤ 0.75) has been prepared and characterised by powder X-ray and neutron diffraction, electrical and thermal transport property measurements, thermal analysis and SQUID magnetometry. With increasing cobalt content, the structure evolves from a disordered arrangement of cobalt ions in octahedral sites located in the van der Waals' gap (x ≤ 0.2), through three different ordered vacancy phases, to a second disordered phase at x ≥ 0.67. Powder neutron diffraction reveals that both octahedral and tetrahedral inter-layer sites are occupied in Co0.67TiS2. Charge transfer from the cobalt guest to the TiS2 host affords a systematic tuning of the electrical and thermal transport properties. At low levels of cobalt intercalation (x andlt; 0.1), the charge transfer increases the electrical conductivity sufficiently to offset the concomitant reduction in |S|. This, together with a reduction in the overall thermal conductivity leads to thermoelectric figures of merit that are 25% higher than that of TiS2, ZT reaching 0.30 at 573 K for CoxTiS2 with 0.04 ≤ x ≤ 0.08. Whilst the electrical conductivity is further increased at higher cobalt contents, the reduction in |S| is more marked due to the higher charge carrier concentration. Furthermore both the charge carrier and lattice contributions to the thermal conductivity are increased in the electrically conductive ordered-vacancy phases, with the result that the thermoelectric performance is significantly degraded. These results illustrate the competition between the effects of charge transfer from guest to host and the disorder generated when cobalt cations are incorporated in the inter-layer space. © The Royal Society of Chemistry 2016.

Published
2016

12. Structural stability of the synthetic thermoelectric ternary and nickel-substituted tetrahedrite phases

Author

Oleg I. Lebedev, Emmanuel Guilmeau, Pierric Lemoine, Ronald I. Smith, Tristan Barbier, Anthony V. Powell, Stéphanie Gascoin, Andreas Kaltzoglou, Paz Vaqueiro, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), University of Reading (UOR), ISIS, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), ISIS Facility, STFC Rutherford Appleton Laboratory (RAL), and Science and Technology Facilities Council (STFC)-Science and Technology Facilities Council (STFC)

Subjects
Materials science, Tetrahedrite, Neutron diffraction, Analytical chemistry, Spark plasma sintering, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY, Thermoelectric effect, ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION, Materials Chemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM]Chemical Sciences, High-resolution transmission electron microscopy, Rietveld refinement, Mechanical Engineering, Metals and Alloys, Powder X-ray diffraction, [CHIM.MATE]Chemical Sciences/Material chemistry, Neutron powder diffraction, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Crystallography, Mechanics of Materials, engineering, 0210 nano-technology, Ternary operation, High temperature characterization, Powder diffraction, Transmission electron microscopy, MathematicsofComputing_DISCRETEMATHEMATICS, Thermoelectric compound
Abstract

International audience; The purity and structural stability of the high thermoelectric performance Cu12Sb4S13 and Cu10.4Ni1.6Sb4S13 tetrahedrite phases, synthesized by solid-liquid-vapor reaction and Spark Plasma Sintering, were studied at high temperature by Rietveld refinement using high resolution X-ray powder diffraction data, DSC/TG measurements and high resolution transmission electron microscopy. In a complementary study, the crystal structure of Cu10.5Ni1.5Sb4S13 as a function of temperature was investigated by powder neutron diffraction. The temperature dependence of the structural stability of ternary Cu12Sb4S13 is markedly different to that of the nickel-substituted phases, providing clear evidence for the significant and beneficial role of nickel substitution on both sample purity and stability of the tetrahedrite phase. Moreover, kinetic effects on the phase stability/decomposition have been identified and discussed in order to determine the maximum operating temperature for thermoelectric applications. The thermoelectric properties of these compounds have been determined for high density samples (>98%) prepared by Spark Plasma Sintering and therefore can be used as reference values for tetrahedrite samples. The maximum ZT of 0.8 was found for Cu10.4Ni1.6Sb4S13 at 700 K. © 2015 Elsevier B.V.

Published
2015

13. Cu-Doping Effect on Dielectric Properties of Organic Gel Synthesized Ba4YMn3-xCuxO11.5±δ

Author

Cécile Autret-Lambert, François Gervais, Antoine Ruyter, Tristan Barbier, Pascal Andreazza, Sébastien Lambert, Christophe Honstettre, Marc Lethiecq, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Université de Tours (UT)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche sur la Matière Divisée (CRMD), Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), CEA Le Ripault (CEA Le Ripault), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Permittivity, Materials science, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Dielectric, Stacking faults, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Inorganic Chemistry, 0103 physical sciences, Materials Chemistry, Physical and Theoretical Chemistry, 010306 general physics, Perovskite (structure), Hexagonal perovskite, Doping, technology, industry, and agriculture, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, Copper, Electronic, Optical and Magnetic Materials, X-ray diffraction, Crystallography, chemistry, Colossal permittivity, X-ray crystallography, Ceramics and Composites, Grain boundary, 0210 nano-technology, Transmission electron microscopy
Abstract

Copper doped-Ba 4 Y Mn 3− x Cu x O 11.5± δ samples were synthesized by an organic gel assisted citrate process. X-ray diffraction of compositions with x =0.002, 0.005, 0.01, 0.02 and 0.04 does not reveal any change of hexagonal perovskite structure on doping. The effects of Cu-doping on the microstructure and dielectric properties were investigated. Cu doping modifies the electrical properties at the level of the impedance characteristics of both grain and grain boundary and to understand these different behaviours, we have carried out high-resolution transmission electron microscopy analysis. Among the Ba 4 Y Mn 3− x Cu x O 11.5± δ specimens studied, the composition x =0.002 shows a permittivity ( e ′ r ) higher than the undoped compound and a lower loss tangent (tan δ ) over several orders of magnitude of frequency.

Published
2013

14. Dielectric Properties of Hexagonal Perovskite Ceramics Prepared by Different Routes

Author

Tristan Barbier, Christophe Honstrette, Cécile Autret-Lambert, François Gervais, Marc Lethiecq, GREMAN (matériaux, microélectronique, acoustique et nanotechnologies) (GREMAN - UMR 7347), Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Materials science, Mechanical Engineering, Analytical chemistry, Mineralogy, 02 engineering and technology, Dielectric, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Grain size, Dielectric spectroscopy, [SPI]Engineering Sciences [physics], Mechanics of Materials, visual_art, Phase (matter), 0103 physical sciences, visual_art.visual_art_medium, Dissipation factor, General Materials Science, Grain boundary, Ceramic, 0210 nano-technology, Perovskite (structure)
Abstract

In this work, four different methods, i.e. solid state reaction, citrate sol–gel process, Pechini and microwave are employed to synthesize Ba4YMn3O11.5±δ ceramics. The phase structure of the powders can be well indexed as a 12R hexagonal perovskite crystallizing in space group R 3 ¯ m . The density and morphology (average grain size) of sintered samples vary with the synthesis processes. The dielectric permittivity and loss tangent of the samples have been measured in the frequency range 1 kHz–1 MHz. The results show that they are very sensitive to the synthesis process. The best properties are obtained for the sample synthetized by citrate process. This compound has a high dielectric permittivity ( e ′ r = 10 4 ), which is almost frequency independent over the 100 Hz–100 kHz range from room temperature to 150 °C. This has been attributed to the IBLC mechanism. By impedance spectroscopy analysis, all the compounds were found to be electrically heterogeneous, exhibiting semiconducting grains and insulating grain boundaries. Finally, we show that the IBLC model is well adapted to the materials obtained by the modified citrate synthesis route, but not to the ones from the other routes.

Published
2012

15. Thermoelectric Properties of (BaCoO3-y)n BaCo8O11.

Author

Ryoji Funahashi and Tristan Barbier

Subjects
*THERMOELECTRIC effects, *HOMOLOGOUS chromosomes, *THERMAL conductivity, *THERMAL properties of condensed matter, *ELECTRICAL resistivity
Abstract

Thermoelectric properties of a homologous oxide system of (BaCoO3-y)nBaCo8O11 have been investigated at 373-973 K in air. All samples show positive Seebeck coefficient values, S, namely p-type character. Electrical resistivity, ρ of BaCoO3-y (n = ∞) decreases monotonically with increasing temperature. On the other hand, a transition in the electrical conduction is observed in the BaCo8O11 (n = 0), Ba2Co9O14 (n = 1), and Ba3Co10O17 (n = 2) around 500 K. Thermal conductivity looks to be decreased by the corner shared CoO6 structure. As the result of these properties, values of dimension-less figure of merit, ZT increase with increasing temperature and reach about 0.03 at 973 K for Ba2Co9O14. Cationic substitution at the Ba site has been carried out. The composition is Ba1.9M0.1Co9O14 (M: Na, Ca, Sr, and La). The substitution by Na is the most effective to enhance the S values at temperatures lower than 573 K. The values of power factor (= S2/ρ) for the samples substituted by Na and Sr are reach 0.1 mW/m.K2 at 773 K. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
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16. Thermoelectric Properties of (BaCoO3-y)n BaCo8O11.

Author

Ryoji Funahashi and Tristan Barbier

Subjects
THERMOELECTRIC effects, HOMOLOGOUS chromosomes, THERMAL conductivity, THERMAL properties of condensed matter, ELECTRICAL resistivity
Abstract

Thermoelectric properties of a homologous oxide system of (BaCoO3-y)nBaCo8O11 have been investigated at 373-973 K in air. All samples show positive Seebeck coefficient values, S, namely p-type character. Electrical resistivity, ρ of BaCoO3-y (n = ∞) decreases monotonically with increasing temperature. On the other hand, a transition in the electrical conduction is observed in the BaCo8O11 (n = 0), Ba2Co9O14 (n = 1), and Ba3Co10O17 (n = 2) around 500 K. Thermal conductivity looks to be decreased by the corner shared CoO6 structure. As the result of these properties, values of dimension-less figure of merit, ZT increase with increasing temperature and reach about 0.03 at 973 K for Ba2Co9O14. Cationic substitution at the Ba site has been carried out. The composition is Ba1.9M0.1Co9O14 (M: Na, Ca, Sr, and La). The substitution by Na is the most effective to enhance the S values at temperatures lower than 573 K. The values of power factor (= S2/ρ) for the samples substituted by Na and Sr are reach 0.1 mW/m.K2 at 773 K. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
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