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Title: High resolution electron energy loss spectroscopy of manganese oxides: Application to Mn{sub 3}O{sub 4} nanoparticles

Abstract

Manganese oxides particularly Mn{sub 3}O{sub 4} Hausmannite are currently used in many industrial applications such as catalysis, magnetism, electrochemistry or air contamination. The downsizing of the particle size of such material permits an improvement of its intrinsic properties and a consequent increase in its performances compared to a classical micron-sized material. Here, we report a novel synthesis of hydrophilic nano-sized Mn{sub 3}O{sub 4}, a bivalent oxide, for which a precise characterization is necessary and for which the determination of the valency proves to be essential. X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and particularly High Resolution Electron Energy Loss Spectroscopy (HREELS) allow us to perform these measurements on the nanometer scale. Well crystallized 10-20 nm sized Mn{sub 3}O{sub 4} particles with sphere-shaped morphology were thus successfully synthesized. Meticulous EELS investigations allowed the determination of a Mn{sup 3+}/Mn{sup 2+} ratio of 1.5, i.e. slightly lower than the theoretical value of 2 for the bulk Hausmannite manganese oxide. This result emphasizes the presence of vacancies on the tetrahedral sites in the structure of the as-synthesized nanomaterial. - Research Highlights: {yields}Mn{sub 3}O{sub 4} bulk and nano were studied by XRD, TEM and EELS. {yields}XRD and TEM determine the degree of crystallinity and themore » narrow grain size. {yields}HREELS gave access to the Mn{sup 3+}/Mn{sup 2+} ratio. {yields}Mn{sub 3}O{sub 4} nano have vacancies on the tetrahedral sites.« less

Authors:
 [1];  [2]
  1. Institut Carnot, Laboratoire CIRIMAT (equipe MEMO), CNRS UMR 5085, ENSIACET, 4 allee Emile Monso, BP 74233, 31432 Toulouse cedex 4 (France)
  2. Laboratoire de Reactivite et Chimie des Solides CNRS UMR 6007, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens cedex 9 (France)
Publication Date:
OSTI Identifier:
22066246
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 61; Journal Issue: 11; Other Information: Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; CATALYSIS; ELECTROCHEMISTRY; ENERGY-LOSS SPECTROSCOPY; GRAIN SIZE; MAGNETISM; MANGANESE IONS; MANGANESE OXIDES; MORPHOLOGY; NANOSTRUCTURES; PARTICLE SIZE; PARTICLES; SYNTHESIS; TRANSMISSION ELECTRON MICROSCOPY; VACANCIES; VALENCE; X-RAY DIFFRACTION

Citation Formats

Laffont, L., E-mail: Lydia.laffont@ensiacet.fr, and Gibot, P.. High resolution electron energy loss spectroscopy of manganese oxides: Application to Mn{sub 3}O{sub 4} nanoparticles. United States: N. p., 2010. Web. doi:10.1016/J.MATCHAR.2010.09.001.
Laffont, L., E-mail: Lydia.laffont@ensiacet.fr, & Gibot, P.. High resolution electron energy loss spectroscopy of manganese oxides: Application to Mn{sub 3}O{sub 4} nanoparticles. United States. doi:10.1016/J.MATCHAR.2010.09.001.
Laffont, L., E-mail: Lydia.laffont@ensiacet.fr, and Gibot, P.. Mon . "High resolution electron energy loss spectroscopy of manganese oxides: Application to Mn{sub 3}O{sub 4} nanoparticles". United States. doi:10.1016/J.MATCHAR.2010.09.001.
@article{osti_22066246,
title = {High resolution electron energy loss spectroscopy of manganese oxides: Application to Mn{sub 3}O{sub 4} nanoparticles},
author = {Laffont, L., E-mail: Lydia.laffont@ensiacet.fr and Gibot, P.},
abstractNote = {Manganese oxides particularly Mn{sub 3}O{sub 4} Hausmannite are currently used in many industrial applications such as catalysis, magnetism, electrochemistry or air contamination. The downsizing of the particle size of such material permits an improvement of its intrinsic properties and a consequent increase in its performances compared to a classical micron-sized material. Here, we report a novel synthesis of hydrophilic nano-sized Mn{sub 3}O{sub 4}, a bivalent oxide, for which a precise characterization is necessary and for which the determination of the valency proves to be essential. X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and particularly High Resolution Electron Energy Loss Spectroscopy (HREELS) allow us to perform these measurements on the nanometer scale. Well crystallized 10-20 nm sized Mn{sub 3}O{sub 4} particles with sphere-shaped morphology were thus successfully synthesized. Meticulous EELS investigations allowed the determination of a Mn{sup 3+}/Mn{sup 2+} ratio of 1.5, i.e. slightly lower than the theoretical value of 2 for the bulk Hausmannite manganese oxide. This result emphasizes the presence of vacancies on the tetrahedral sites in the structure of the as-synthesized nanomaterial. - Research Highlights: {yields}Mn{sub 3}O{sub 4} bulk and nano were studied by XRD, TEM and EELS. {yields}XRD and TEM determine the degree of crystallinity and the narrow grain size. {yields}HREELS gave access to the Mn{sup 3+}/Mn{sup 2+} ratio. {yields}Mn{sub 3}O{sub 4} nano have vacancies on the tetrahedral sites.},
doi = {10.1016/J.MATCHAR.2010.09.001},
journal = {Materials Characterization},
number = 11,
volume = 61,
place = {United States},
year = {Mon Nov 15 00:00:00 EST 2010},
month = {Mon Nov 15 00:00:00 EST 2010}
}
  • High-resolution electron-energy-loss spectroscopy has been performed for a polycrystalline sample of YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ in the temperature range between 300 and 45 K. A pronounced surface-conductivity transition is observed between 100 and 200 K both via the inelastically and elastically scattered electrons.
  • As the primary source of atmospheric dioxygen, photosynthetic water oxidation is an essential process for aerobic organisms. This four-electron, four-proton reaction occurs at the photosystem II oxygen-evolving complex (PSII OEC) in green plants and algae. While it is known that four manganese atoms per PSII OEC are required for optimal oxygen evolution activity, there is no consensus as to the precise arrangement of the Mn atoms, nor is the mechanism of water oxidation well understood. In this report we describe the synthesis and structure of a novel mixed-valence (Mn{sup II}{sub 2}Mn{sup III}{sub 2}) tetranuclear complex. ((Mn{sub 2}(TPHPN)(O{sub 2}CC-H{sub 2})(H{sub 2}O)){submore » 2}O)(ClO{sub 4}){sub 4}. (1), which does indeed display several quasireversible oxidations between 0.8 and 1.4 V vs SSCE.« less
  • Photosynthetic water oxidation is thought to occur at a polynuclear manganese aggregate within the photosystem II oxygen-evolving complex (PSII OEC). While X-ray absorption studies have established that Mn{hor ellipsis}Mn contacts of 2.7 and 3.3 {angstrom} are present in the OEC, the precise structure of the manganese aggregate has not been established. We are currently taking a synthetic analogue approach in order to elucidate this important biological process. Herein, we describe a novel tetranuclear complex. (Mn{sub 4}O{sub 2}(TPHPN){sub 2}(H{sub 2}O){sub 2}(CF{sub 3}SO{sub 3}){sub 2}){sup 3+} (1), which meets several important criteria for a synthetic analogue of the OEC manganese center inmore » that it has a 2.7-{angstrom} Mn{hor ellipsis}Mn contact, coordinated H{sub 2}O molecules, and quasi-reversible electrochemical properties.« less
  • High-resolution electron-energy-loss spectroscopy has been used to determine the magnitude and temperture dependence of the energy gap for oxygen annealed Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystals. Below the {ital T}{sub {ital c}}, low-energy excitations are detected in the energy-loss spectra. These spectra are proportional to the frequency-dependent resistivity, {rho}({omega}), and thus the energy gap can be determined directly from the onset of {rho}({omega}). We find that at low temperature 2{Delta}=6{ital kT}{sub {ital c}} and that {Delta} develops sharply for {ital T}{lt}{ital T}{sub {ital c}}. The similarity of these results to the predictions of models that consider spin interactions suggestsmore » that higher {ital T}{sub {ital c}}'s may be obtainable in this material.« less
  • High-resolution electron-energy-loss spectroscopy (HREELS) has been used to study the adsorption and uv-laser-induced dissociation of Al/sub 2/(CH/sub 3/)/sub 6/ (trimethylaluminum (TMA)) on Si(100)2 x 1 and Si(111)7 x 7 surfaces. Single-layer adsorption was obtained for substrate temperatures T/sub s/ between 180 and 200 K, while multilayer deposition occurred for T/sub s/<180 K. Low-energy electron diffraction patterns showed no evidence of long-range order in either the single-layer or multilayer deposits. HREELS spectra from TMA single layers adsorbed on Si(100)2 x 1 and Si(111)7 x 7 were consistent with those expected for nondissociatively adsorbed TMA dimers whose Al-Al axes are orthogonal tomore » the substrate surface. No changes in the adlayer spectra were observed under KrF-laser irradiation (248 nm, 5.0 eV, 20-ns pulses) even after 10/sup 4/ pulses with intensities up to 200 mJcm/sup -2/ per pulse. Low-intensity (20mJcm/sup -2/) ArF-laser irradiation (193 nm, 6.4 eV, 20-ns pulses), however, led to monomerization of the adsorbate. Higher-intensity (200 mJ cm/sup -2/) ArF-laser irradiation caused dissociation of the TMA monomer and desorption of some methyl ligands. Both KrF- and ArF-laser irradiation of multilayer samples gave rise to immediate thermally induced desorption of loosely bound upper layers, while the remaining adlayer behaved in a manner similar to that of the single-layer samples.« less