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5. Importance of lattice softness and phonon anharmonicity for the optoelectronic properties of 3D, 2D and 0D halide perovskites

Author

Even, Jacky, Da Cunha Ferreira, Afonso, Paofai, Serge, Létoublon, Antoine, Ollivier, Jacques, Raymond, stéphane, Sébastien, Clément, VIALLA, Remy, HEHLEN, Bernard, RUFFLE, Benoit, Cordier, Stéphane, Katan, Claudine, Bourges, Philippe, Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), 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), Institut Laue-Langevin (ILL), Magnétisme et Diffusion Neutronique (MDN ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), European Project: 899141,PoLLoC, European Project: PeroCUBE, European Project: 862656,DROPIT, Université de Rennes 1 (UR1), 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)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), 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), ILL, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay

Subjects
[PHYS]Physics [physics], [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2021

8. Elastic softness of hybrid lead halide perovskites

Author

Ferreira, Afonso, Létoublon, Antoine, Paofai, Serge, Raymond, Stephane, Ecolivet, Claude, Ruffle, Benoit, Cordier, Stéphane, Katan, Claudine, Saidaminov, Makhsud, Bakr, Osman, Even, Jacky, Bourges, Philippe, Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), Université de Rennes 1 (UR1), 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)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), 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), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut de Physique de Rennes (IPR), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), King Abdullah University of Science and Technology (KAUST), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS), 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), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], [CHIM]Chemical Sciences
Abstract

National audience; Much recent attention has been devoted towards unraveling the microscopic optoelectronic properties of hybrid organic-inorganic perovskites. Here we investigate by coherent inelastic neutron scattering spectroscopy and Brillouin light scattering, low frequency acoustic phonons in four different hybrid perovskite single crystals: MAPbBr_{3}, FAPbBr_{3}, MAPbI_{3}, and α-FAPbI_{3} (MA: methylammonium, FA: formamidinium). We report a complete set of elastic constants characterized by a very soft shear modulus C_{44}. Further, a tendency towards an incipient ferroelastic transition is observed in FAPbBr_{3}. We observe a systematic lower sound group velocity in the technologically important iodide-based compounds compared to the bromide-based ones. The findings suggest that low thermal conductivity and hot phonon bottleneck phenomena are expected to be enhanced by low elastic stiffness, particularly in the case of the ultrasoft α-FAPbI_{3}.

Published
2018

9. Low-frequency Raman spectroscopy and elastic softness of hybrid lead halide perovskites

Author

Hehlen, Bernard, RUFFLE, Benoit, Da Cunha Ferreira, Afonso, Bourges, Philippe, Létoublon, Antoine, Paofai, Serge, Cordier, Stéphane, Ecolivet, Claude, Raymond, stéphane, Bakr, Osman, Katan, Claudine, Even, Jacky, Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), LLB - Nouvelles frontières dans les matériaux quantiques (NFMQ), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), 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), Groupe matière condensée et matériaux (GMCM), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Magnétisme et Diffusion Neutronique (MDN), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), King Abdullah University of Science and Technology (KAUST), European Project: 687008,H2020,H2020-FETOPEN-2014-2015-RIA,GOTSolar(2016), Université de Rennes 1 (UR1), 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)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, 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), Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

National audience; Hybrid organic-inorganic perovskites are intensively studied as promising materials for various applications, taking advantage of their low cost and easy processing. Although much recent attention has been devoted towards unraveling their microscopic optoelectronic properties, the low frequency dynamics (e.g. their softness) is currently still lacking a comprehensive understanding as compared to that already reached for classic semiconductors. Here we investigate the low frequency dynamics in four different hybrid perovskite single crystals: MAPbBr3, FAPbBr3, MAPbI3 and α-FAPbI3. Using coherent inelastic neutron scattering spectroscopy and Brillouin light scattering, we investigate the low frequency acoustic phonons [1,2]. A very small shear C44 elastic constant is found for all the compounds as well as sizeable elastic anisotropy. The extremely low bulk modulus and negative C12 in α-FAPbI3 substantiates its very unstable nature and in FAPbBr3, a tendency towards an incipient ferroelastic transition, is interpreted as further evidence of the influence of plasticity in hybrid perovskites. We observe a systematic lower sound group velocity in the technologically important iodide-based compounds compared to the bromide-based ones [2]. The findings suggest that low thermal conductivity and hot phonon bottleneck phenomena are expected to be enhanced by low elastic stiffness, particularly in the case of the ultrasoft α-FAPbI3 (Fig. 1a).The low-frequency dynamics is further investigated by Raman spectroscopy. The scattering from the low-frequency optical phonons has been collected across the cubic to tetragonal transition. With the resolution and contrast available by our experiment (~4-5 cm-1 at the bottom of the elastic line) we do not observe the divergence of a central peak. However, the lowest frequency vibration, almost temperature independent in the cubic phase, hardens on cooling in the tetragonal phase. These conclusions apply in three of the four samples (analysis in α-FAPI still in progress) suggesting a common framework for the analysis of the low-frequency vibrational dynamics of this family compounds (Fig. 1b). In CH3NH3PbI3 the Raman spectroscopy across the full set of phase transitions down to 20 K will also be discussed.

Published
2018

12. Evidencing ((n-C4H9)4N)2[W6I14] red–NIR emission and singlet oxygen generation by two photon absorption.

Author

Molard, Yann, Taupier, Gregory, Paofai, Serge, and Cordier, Stéphane

Subjects
REACTIVE oxygen species, LIGHT absorption, TUNGSTEN compounds, PHOTODYNAMIC therapy, TUNGSTEN, OPTOELECTRONICS
Abstract

We report the first proof of the ability of octahedral tungsten clusters to emit red–NIR light and to produce singlet oxygen upon two-photon absorption, in solution and in the solid-state. Such discoveries open new perspectives for tungsten cluster compounds in several fields like optoelectronics, photodynamic therapy, and bioimaging. [ABSTRACT FROM AUTHOR]

Published
2021
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13. Structural and dynamic properties of hybrid perovskites for photovoltaic applications

Author

da Cunha Ferreira, Afonso, Létoublon, Antoine, Raymond, Stéphane, Paofai, Serge, Cordier, Stéphane, Katan, Claudine, Saidaminov, Makshud, Zhumekenov, Ayan, Bakr, Osman, Even, Jacky, Bourges, Philippe, Institut des Fonctions Optiques pour les Technologies de l'informatiON (Institut FOTON), École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-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)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES), Magnetic Resonance (RM ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), 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), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), 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 (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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-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)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2017

14. In situ exsolution of Ni particles on the PrBaMn2O5 SOFC electrode material monitored by high temperature neutron powder diffraction under hydrogen.

Author

Bahout, Mona, Managutti, Praveen B., Dorcet, Vincent, Le Gal La Salle, Annie, Paofai, Serge, and Hansen, Thomas C.

Abstract

NiO has been incorporated into the Pr0.5Ba0.5MnO3−δ perovskite to produce, upon heating under a hydrogen atmosphere, in situ exsolved Ni-catalysts supported on the PrBaMn2O5 anode material. Transmission electron microscopy (TEM) and neutron powder diffraction (NPD) showed that the initial composition obtained by annealing in air at 950 °C consists of two perovskite phases: orthorhombic Pr0.65Ba0.35Mn0.975Ni0.025O3 (S.G. Ibmm, ∼75 wt%) and 2H-hexagonal BaMnO3−δ (S.G. P63/mcm, ∼25 wt%). On heating the two-phase sample under wet hydrogen, MnO particles exsolve at T ∼ 500 °C meanwhile the orthorhombic phase transforms to tetragonal (S.G. I4/mcm) then to cubic (S.G. Pm3¯m) at T ∼ 665 °C. When the temperature approaches 900 °C, the emergence of Ni metal particles was detected in the neutron diffraction patterns meanwhile the two perovskite phases start to transform into a Ni-free layered double perovskite, PrBaMn2O5. In situ real time observation of the structural changes under hydrogen atmosphere provided evidence of the simultaneity of Ni exsolution and phase transformation within our timescale resolution. From quantitative Rietveld analysis, the fraction of exsolved nickel represents the whole amount of Ni introduced in the synthesis. Impedance spectroscopy measurements in a 5% H2/Ar atmosphere show promising electrochemical performance for the Ni-exsolved layered perovskite electrode with a polarization resistance of 0.4 Ω cm2 at 800 °C (0.135 Ω cm2 at 850 °C) without any optimization. [ABSTRACT FROM AUTHOR]

Published
2020
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15. When a Red–NIR‐Emissive Cs2[Mo6Br14] Interacts with an Active Diureasil–PEO Matrix: Design of Tunable and White‐Light‐Emitting Hybrid Material.

Author

Ferreira Molina, Eduardo, Martins de Jesus, Natana Aparecida, Paofai, Serge, Hammer, Peter, Amela‐Cortes, Maria, Robin, Malo, Cordier, Stephane, and Molard, Yann

Subjects
ENERGY transfer, MOLYBDENUM, METAL clusters, CESIUM compounds
Abstract

Hybrid materials that combine diureasil matrices and octahedral molybdenum clusters have been synthesized to design lead‐, cadmium‐ and rare‐earth‐free emitters for lighting or optoelectronic applications. This association leads to homogeneous and stable hybrids, for which the emission color can be tailored in the entire visible range, including white light; this is thanks to effective energy transfers from the host to the nanocluster. [ABSTRACT FROM AUTHOR]

Published
2019
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18. Metal Atom Clusters as Building Blocks for Multifunctional Proton-Conducting Materials: Theoretical and Experimental Characterization

Author

Daigre, Gilles, primary, Cuny, Jérôme, additional, Lemoine, Pierric, additional, Amela-Cortes, Maria, additional, Paofai, Serge, additional, Audebrand, Nathalie, additional, Le Gal La Salle, Annie, additional, Quarez, Eric, additional, Joubert, Olivier, additional, Naumov, Nikolay G., additional, and Cordier, Stéphane, additional

Published
2018
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19. Plastic crystal behavior, tight-binding modelling and low energy phonon spectroscopy in hybrid perovskites crystals

Author

Even, Jacky, Paofai, Serge, Bourges, Philippe, Létoublon, Antoine, Cordier, Stéphane, Durand, Olivier, Boyer-Richard, Soline, Jancu, Jean-Marc, Rufflé, Benoit, Ecolivet, Claude, Carignano, Marcelo, Katan, Claudine, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), 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), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Qatar Environment and Energy Research Institute (QEERI), ANR-15-CE05-0023,SuperSansPlomb,Cellule Solaire Utilisant des Pérovskites Hybrides Sans Plomb(2015), ANR-12-BS10-0011,SNAP,Nano-plaquettes colloïdales atomiquement plates(2012), European Project: 687008,H2020,H2020-FETOPEN-2014-2015-RIA,GOTSolar(2016), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-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)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-Télécom Bretagne, 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), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), KATAN, Claudine, Captage des énergies renouvelables et récupération des énergies de l’environnement - Cellule Solaire Utilisant des Pérovskites Hybrides Sans Plomb - - SuperSansPlomb2015 - ANR-15-CE05-0023 - AAPG2015 - VALID, BLANC - Nano-plaquettes colloïdales atomiquement plates - - SNAP2012 - ANR-12-BS10-0011 - BLANC - VALID, and New technological advances for the third generation of Solar cells - GOTSolar - - H20202016-01-01 - 2018-12-31 - 687008 - VALID

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [CHIM.THEO] Chemical Sciences/Theoretical and/or physical chemistry, Condensed Matter::Materials Science, Condensed Matter::Strongly Correlated Electrons
Abstract

International audience; In this paper, we examine recent theoretical investigations on 3D hybrid perovskites (HOP) that combine concepts developed for classical bulk solid-state physics and empirical simulations of their optoelectronic properties. In fact, the complexity of HOP calls for a coherent global view that combines usually disconnected concepts, related to classical semiconductors, perovskites and plastic crystals1. For the pseudocubic high temperature reference perovskite structure that plays a central role for 3D HOP, we introduce a new tight-binding Hamiltonian, which specifically includes spin-orbit coupling. The resultant electronic band structure is compared to that obtained using state of the art density functional theory (DFT). Possible plastic crystal and orientational glass behaviors of HOP will be discussed, building on Car-Parrinello molecular dynamics simulations and symmetry analyses of the cation stochastic reorientations. As available experimental or simulated data on low energy structural excitations are limited, large single crystals of MAPbBr3 have been grown and used to perform neutron and Brillouin scattering and ultrasonic characterization of low frequency acoustic phonons, as well as relaxation modes in different energy ranges. Neutron scattering experiments further reveal that the MAPbBr3 crystal presents a coexistence of crystalline domains below the cubic to tetragonal phase transition at Tc=225K. This observation is consistent with the improper ferroelastic character of the phase transition as predicted from the symmetry analysis of phonon and molecular relaxational modes. [1]Even, J., Carignano, M. & Katan, C. “Molecular disorder and translation/rotation coupling in the plastic crystal phase of hybrid perovskites.” Nanoscale DOI: 10.1039/C5NR06386H, (2016)

Published
2016

20. Raman and Brillouin scattering from single crystals of CH3NH3PbBr3 around the cubic to tetragonal phase transition

Author

Létoublon, Antoine, Paofai, Serge, Ruffle, Benoit, Hehlen, Bernard, Ecolivet, Claude, Katan, Claudine, Even, Jacky, Aigle, L2c, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-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)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-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), Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-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), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], ComputingMilieux_MISCELLANEOUS, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

National audience; .

Published
2016

21. Low energy phonon spectroscopy and translation-rotation coupling in hybrid perovskites crystals

Author

Létoublon, Antoine, Paofai, Serge, Bourges, Philippe, Cordier, Stéphane, Durand, Olivier, Rufflé, Benoit, Ecolivet, Claude, Carignano, Marcelo, Katan, Claudine, Even, Jacky, KATAN, Claudine, New technological advances for the third generation of Solar cells - GOTSolar - - H20202016-01-01 - 2018-12-31 - 687008 - VALID, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), 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), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Qatar Environment and Energy Research Institute (QEERI), European Project: 687008,H2020,H2020-FETOPEN-2014-2015-RIA,GOTSolar(2016), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-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)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-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), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], [PHYS.COND] Physics [physics]/Condensed Matter [cond-mat]
Abstract

National audience; Despite the wealth of research conducted the last three years on hybrid organic perovskites (HOP), several questions remain open including: to what extend the organic moiety changes the properties of the material as compared to all-inorganic (AIP) related perovskite structures. To ultimately reach an answer to this question, we have recently introduced two approaches that were designed to take the stochastic molecular degrees of freedom into account, and suggested that the high temperature cubic phase of HOP and AIP is an appropriate reference phase to rationalize HOP's properties. In this paper, we recall the main concepts and show recent molecular dynamic results (figure 1) to discuss more specifically the various possible couplings between charge carriers and low energy excitations such as acoustic and optical phonons. As available experimental or simulated data on low energy excitations are limited, we also present preliminary neutron and Brillouin scattering, as well as ultrasonic measurements obtained on freshly prepared single crystals of CH 3 NH 3 PbBr 3.

Published
2016

22. Mo6 cluster-based compounds for energy conversion applications: comparative study of photoluminescence and cathodoluminescence

Author

Dierre, Benjamin, primary, Costuas, Karine, additional, Dumait, Noée, additional, Paofai, Serge, additional, Amela-Cortes, Maria, additional, Molard, Yann, additional, Grasset, Fabien, additional, Cho, Yujin, additional, Takahashi, Kohsei, additional, Ohashi, Naoki, additional, Uchikoshi, Tetsuo, additional, and Cordier, Stéphane, additional

Published
2017
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23. New ultra-violet and near-infrared blocking filters for energy saving applications: fabrication of tantalum metal atom cluster-based nanocomposite thin films by electrophoretic deposition

Author

Nguyen, Thi Kim Ngan, primary, Renaud, Adèle, additional, Wilmet, Maxence, additional, Dumait, Noée, additional, Paofai, Serge, additional, Dierre, Benjamin, additional, Chen, Wanghui, additional, Ohashi, Naoki, additional, Cordier, Stéphane, additional, Grasset, Fabien, additional, and Uchikoshi, Tetsuo, additional

Published
2017
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26. Photoreduction of CO 2 to methanol with hexanuclear molybdenum [Mo 6 Br 14 ] 2À cluster units under visible light irradiation † RSC Advances COMMUNICATION

Author

Kumar, Pawan, Kumar, Subodh, Cordier, Stéphane, Paofai, Serge, Boukherroub, Rabah, Jain, Suman, National Institute of Technology [Patna] (NIT), Institut des Sciences Chimiques de Rennes (ISCR), 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), Institut de Recherche Interdisciplinaire [Villeneuve d'Ascq] (IRI), Université de Lille, Sciences et Technologies-Université de Lille, Droit et Santé-Centre National de la Recherche Scientifique (CNRS), The George Washington University (GW), 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), and Centre National de la Recherche Scientifique (CNRS)-Université de Lille, Droit et Santé-Université de Lille, Sciences et Technologies

Subjects
[SDE]Environmental Sciences, [CHIM]Chemical Sciences
Abstract

International audience; Octahedral molybdenum clusters were found to be efficient visible light homogeneous photocatalysts for the reduction of carbon dioxide (CO 2) to methanol. Photoreduction was carried out by using 20 watt white cold LED flood light in dimethyl formamide/water or acetoni-trile/water solutions containing triethylamine as a reductive quencher. Among the two cluster-based compounds, Cs 2 [Mo 6 Br 14 ] exhibited higher photocatalytic efficiency and afforded higher yield of methanol than (TBA) 2 [Mo 6 Br 14 ] (TBA ¼ tetrabutylammonium). After 24 h illumination , the yield of methanol was 6679.45 and 5550.53 mmol g À1 cat. using Cs 2 [Mo 6 Br 14 ] and (TBA) 2 [Mo 6 Br 14 ] cluster compounds as photocatalysts, respectively. The continuously increasing concentration of carbon dioxide (CO 2) in the atmosphere has become one of the most serious problems with regard to the greenhouse effect. 1 Photocatalytic reduction of CO 2 with water for the production of hydrocarbons could be one of the viable solutions to address the issues related to climate change as well as energy shortage. 2 Over the past few decades, extensive efforts have been devoted to develop visible light active photocatalytic materials as visible light is ubiquitous , renewable and clean source of energy. 3 Although semiconductors such as TiO 2 , ZnS, and CdS have widely been used as photocatalysts for CO 2 reduction, their quantum yields and selectivities of products are low. 4 Homogeneous photocatalysts, including transition metal complexes such as ruthenium(II) polypyridine carbonyl complex, 5 cobalt(II) trisbipyridine, 6 and cobalt(III) macrocycles 7 have been widely investigated for this reaction. Enzyme catalysts have also been used for such photoreduction processes. 8 Transition metal based molecular complexes are advantageous due to their high quantum effi-ciencies and high selectivity of products. However, in some instances, a weak absorption in the visible region makes the utility of these complexes limited. This limitation can be overcome by using high nuclearity transition metal cluster complexes having the basic formula, [M 6 (m 3-X) 8 L 6 ] 2À , which is also written as [Mo 6 X i 8 L a 6 ] 2À (i ¼ inner; a ¼ apical; X ¼ halogen, L ¼ halogen or functional organic ligand). 9 In such face-capped metal atom clusters, the metallic electrons are delocalized on all the metal centers leading to particular intrinsic properties (magnetic, optical, redox processes). These nanosized molecular units exhibit a large absorption window from UV to visible as well as a large emission window from red to infrared due to the delocalization of valence electrons on all metal centers. 10 Molybdenum halide based cluster complexes have been known since a long time and have been used for photochemical processes for energy storage, as singlet oxygen photocatalysts and as bio-imaging agents. 11 However, to the best of our knowledge, these cluster complexes have not been investigated so far for the photocatalytic reduction of CO 2. In the present paper, we wish to report on the use of octa-hedral molybdenum cluster-based compounds Cs 2 [Mo 6 Br 14 ] (i.e. Cs 2 [Mo 6 Br i 8 Br a 6 ]) and (TBA) 2 [Mo 6 Br 14 ] (i.e. (TBA) 2 [Mo 6-Br i 8 Br a 6 ], TBA ¼ tetrabutyl ammonium) as efficient visible light active photocatalysts for the photoreduction of CO 2 to methanol by using water as the reaction medium and triethylamine as a sacricial donor. The synthesis and characterizations of Cs 2 [Mo 6 Br 14 ] and (TBA) 2 [Mo 6 Br] 14 have been fully described in the literature. 12 The structures are based on [Mo 6 X i 8 L a 6 ] 2À cluster units depicted in Fig. 1 as anionic building blocks and Cs + and (TBA) + as counter cations. Initially, Mo 6 Br 12 (Mo 6 Br i 8 Br a–a 4/2 Br a 2) was prepared by the reaction of Br 2 with Mo at 750 C. Then an excision reaction was performed between a stoichiometric amount of MoBr 2 and CsBr at 850 C for two days. Aerwards, Cs 2 Mo 6 Br 14 was dissolved in dry acetone, ltrated and recrystallized in pure form.

Published
2014

27. Elastic Constants, Optical Phonons, and Molecular Relaxations in the High Temperature Plastic Phase of the CH3NH3PbBr3 Hybrid Perovskite

Author

Létoublon, Antoine, primary, Paofai, Serge, additional, Rufflé, Benoît, additional, Bourges, Philippe, additional, Hehlen, Bernard, additional, Michel, Thierry, additional, Ecolivet, Claude, additional, Durand, Olivier, additional, Cordier, Stéphane, additional, Katan, Claudine, additional, and Even, Jacky, additional

Published
2016
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32. Mo6 cluster-based compounds for energy conversion applications: comparative study of photoluminescence and cathodoluminescence.

Author

Dierre, Benjamin, Costuas, Karine, Dumait, Noée, Paofai, Serge, Amela-Cortes, Maria, Molard, Yann, Grasset, Fabien, Cho, Yujin, Takahashi, Kohsei, Ohashi, Naoki, Uchikoshi, Tetsuo, and Cordier, Stéphane

Subjects
CATHODOLUMINESCENCE, ENERGY conversion, PHOTOLUMINESCENCE, METAL clusters, COMPARATIVE studies, LIGANDS (Chemistry), NATURE
Abstract

We report the photoluminescence (PL) and cathodoluminescence (CL) properties of face-capped [Mo6Xi8La6]2− (X = Cl, Br, I; L = organic or inorganic ligands) cluster units. We show that the emission of Mo6 metal atom clusters depends not only on the nature of X and L ligands bound to the cluster and counter-cations, but also on the excitation source. Seven members of the AxMo6Xi8La6 series (A = Cs+, (n-C4H9)4N+, NH4+) were selected to evaluate the influence of counter-cations and ligands on de-excitation mechanisms responsible for multicomponent emission of cluster units. This study evaluates the ageing of each member of the series, which is crucial for further energy conversion applications (photovoltaic, lighting, water splitting, etc.). [ABSTRACT FROM AUTHOR]

Published
2017
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33. Hydride in BaTiO2.5H0.5: A Labile Ligand in Solid State Chemistry

Author

Masuda, Naoya, primary, Kobayashi, Yoji, additional, Hernandez, Olivier, additional, Bataille, Thierry, additional, Paofai, Serge, additional, Suzuki, Hajime, additional, Ritter, Clemens, additional, Ichijo, Naoki, additional, Noda, Yasuto, additional, Takegoshi, Kiyonori, additional, Tassel, Cédric, additional, Yamamoto, Takafumi, additional, and Kageyama, Hiroshi, additional

Published
2015
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36. A-site order–disorder in the NdBaMn2O5+δ SOFC electrode material monitored in situ by neutron diffraction under hydrogen flow.

Author

Tonus, Florent, Bahout, Mona, Dorcet, Vincent, Sharma, Rakesh K., Djurado, Elisabeth, Paofai, Serge, Smith, Ronald I., and Skinner, Stephen J.

Abstract

The A-site disordered perovskite manganite, Nd0.5Ba0.5MnO3, has been obtained by heating the A-site-ordered and vacancy ordered layered double perovskite, NdBaMn2O5, in air at 1300 °C for 5 h. Combined transmission electron microscopy (TEM) images and neutron powder diffraction (NPD) analysis at 25 °C revealed that Nd0.5Ba0.5MnO3 has a pseudotetragonal unit cell with orthorhombic symmetry (space group Imma, √2ap× 2ap×√2ap) at 20 °C with the cell dimensions a = 5.503(1) Å, b = 7.7962(4) Å, c = 5.502(1) Å, in contrast to Pm3̅m or Cmcm that have been previously stated from X-ray diffraction studies. The in situ neutron diffraction study carried out on Nd0.5Ba0.5MnO3 in hydrogen flow up to T∼ 900 °C, allows monitoring the A-site cation disorder–order structural phase transition of this representative member of potential SOFC anode materials between air sintering conditions and hydrogen working conditions. Oxygen loss from Nd0.5Ba0.5MnO3 proceeds with retention of A-site disorder until the oxygen content reaches the Nd0.5Ba0.5MnO2.5 composition at 600 °C. The phase transition to layered NdBaMn2O5 and localization of the oxygen vacancies in the Nd layer proceeds at 800 °C with retention of the oxygen content. Impedance spectroscopy measurements for the oxidized A-site ordered electrode material, NdBaMn2O6, screen printed on a Ce0.9Gd0.1O2−δ (CGO) electrolyte showed promising electrochemical performance in air at 700 °C with a polarization resistance of 1.09 Ω cm2 without any optimization. [ABSTRACT FROM AUTHOR]

Published
2017
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37. Mo 6 cluster-based compounds for energy conversion applications: comparative study of photoluminescence and cathodoluminescence.

Author

Dierre, Benjamin, Costuas, Karine, Dumait, Noée, Paofai, Serge, Amela-Cortes, Maria, Molard, Yann, Grasset, Fabien, Cho, Yujin, Takahashi, Kohsei, Ohashi, Naoki, Uchikoshi, Tetsuo, and Cordier, Stéphane

Subjects
PHOTOLUMINESCENCE, CATHODOLUMINESCENCE, LIGANDS (Chemistry)
Abstract

We report the photoluminescence (PL) and cathodoluminescence (CL) properties of face-capped [Mo6Xi8La6]2−(X = Cl, Br, I; L = organic or inorganic ligands) cluster units. We show that the emission of Mo6metal atom clusters depends not only on the nature of X and L ligands bound to the cluster and counter-cations, but also on the excitation source. Seven members of the AxMo6Xi8La6series (A = Cs+, (n-C4H9)4N+, NH4+) were selected to evaluate the influence of counter-cations and ligands on de-excitation mechanisms responsible for multicomponent emission of cluster units. This study evaluates the ageing of each member of the series, which is crucial for further energy conversion applications (photovoltaic, lighting, water splitting, etc.). [ABSTRACT FROM AUTHOR]

Published
2017
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41. ChemInform Abstract: Unprecedented Electron‐Poor Octahedral Ta6 Clusters in a Solid‐State Compound: Synthesis, Characterizations and Theoretical Investigations of Cs2BaTa6Br15O3.

Author

Demont, Antoine, primary, Prestipino, Carmelo, additional, Hernandez, Olivier, additional, Elkaim, Erik, additional, Paofai, Serge, additional, Naumov, Nikolai, additional, Fontaine, Bruno, additional, Gautier, Regis, additional, and Cordier, Stephane, additional

Published
2013
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45. Redox behavior of the SOFC electrode candidate NdBaMn2O5+δ investigated by high-temperature in situ neutron diffraction: first characterisation in real time of an LnBaMn2O5.5 intermediate phase.

Author

Tonus, Florent, Bahout, Mona, Dorcet, Vincent, Gauthier, Gilles H., Paofai, Serge, Smith, Ronald I., and Skinner, Stephen J.

Abstract

The structural behavior of the tetragonal NdBaMn2O5 phase, a member of the family of A-site ordered layered manganites that have been recently suggested as possible mixed ionic and electronic conductors, has been investigated by means of in situ neutron powder diffraction. Considering applications in energy production and storage devices and use of NdBaMn2O5+δ as an electrode in symmetrical cells, the study was carried out in relevant atmosphere conditions, i.e. dilute hydrogen (wet and dry) and dry air in the temperature range 25–800 °C. Neutron data under flowing hydrogen allowed monitoring of the structural phase transition from the charge-ordered to the charge-disordered state as a function of temperature. Slow reduction of the fully oxidised phase, NdBaMn2O6, previously formed from quick oxidation of the pristine material, enabled real-time observation of the intermediate NdBaMn2O5.5 phase and its crystal characterization up to 700 °C in the course of its conversion to NdBaMn2O5. Oxygen vacancy ordering within the Nd layers of NdBaMn2O5.5 correlated with antiferrodistortive orbital ordering of the Jahn–Teller Mn3+ ion in the square pyramids and octahedra results in large thermal expansion and relatively slow anisotropic oxygen diffusion occurring in the NdO layer. The four heating/cooling cycles evidenced no oxygen miscibility between the three distinct phases detected in the NdBaMn2O5+δ system with δ∼ 0, 0.5 and 1 and clearly demonstrated that reversible oxygen intercalation/deintercalation underpins the phase stability of the LnBaMn2O5+δ materials to redox cycling and to wet atmosphere in high temperature electrochemical devices. [ABSTRACT FROM AUTHOR]

Published
2016
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46. Structure and reactivity with oxygen of Pr2NiO4+δ: an in situ synchrotron X-ray powder diffraction study.

Author

Broux, Thibault, Prestipino, Carmelo, Bahout, Mona, Paofai, Serge, Elkaïm, Erik, Vibhu, Vaibhav, Grenier, Jean-Claude, Rougier, Aline, Bassat, Jean-Marc, and Hernandez, Olivier

Subjects
OXYGEN compounds, CHALCOGENS, NONMETALS, IONIZING radiation, X-rays
Abstract

The promising SOFC cathode material Pr2NiO4.22 has been studied in situ under a pure oxygen atmosphere from 25 to 950 °C by high resolution synchrotron X-ray powder diffraction. At room temperature (RT) δ = 0.22(1), the average crystal structure turns out to be monoclinic. The subtle monoclinic distortion (γ = 90.066(1)° at RT), retained up to 460 °C, is interpreted in terms of specific tilt schemes of the NiO6 octahedra. It is also shown that Pr2NiO4.22 is incommensurately structurally modulated already at room temperature, in the same manner as the homologous cobaltate La2CoO4.14. The phase transition to the High Temperature Tetragonal (HTT) phase was completed at 480 °C without any evidence for the Low Temperature Orthorhombic (LTO) phase allowing clarifying the phase diagram of this K2NiF4-type ternary oxide. Moreover, it turns out that above 800 °C, the HTT phase transforms reversibly into two coexisting isomorphous tetragonal phases. The incommensurate modulation subsists up to 950 °C, although modified concomitantly with the two abovementioned phase transformations. In addition, the role of kinetics on the decomposition process is highlighted through thermo-gravimetric analyses. [ABSTRACT FROM AUTHOR]

Published
2016
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47. Versatility of the ionic assembling method to design highly luminescent PMMA nanocomposites containing [M6Qi8La6]n− octahedral nano-building blocks.

Author

Amela-Cortes, Maria, Molard, Yann, Paofai, Serge, Desert, Anthony, Duvail, Jean-Luc, Naumov, Nikolay G., and Cordier, Stéphane

Subjects
LUMINESCENCE, NANOCOMPOSITE materials, POLYMERIZATION research, CATIONS, CHEMICAL research
Abstract

New luminescent poly(methylmethacrylate) (PMMA) nanocomposites with high content of different hexanuclear octahedral cluster building blocks, namely [Mo6I8(C2F5COO6)]2−, [Re6Se8(CN)6]4− and [W6Cl14]2− have been prepared by free-radical polymerisation. To do so, cluster complexes bearing a polymerisable ammonium counter-cation have been synthesised. In this way, we demonstrate that ionic assembling is a powerful tool to functionalise easily any type of anionic cluster units to be introduced in a PMMA organic matrix. All samples remain homogeneous, stable during several months, and retain the luminescence properties of the cluster precursor. [ABSTRACT FROM AUTHOR]

Published
2016
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