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Title: Charge ordering and multiferroicity in Fe{sub 3}BO{sub 5} and Fe{sub 2}MnBO{sub 5} oxyborates

Abstract

The comparison of Fe{sub 3}BO{sub 5} and Fe{sub 2}MnBO{sub 5} reveals that the 2Fe{sup 2+}: Fe{sup 3+} charge ordering of the former is suppressed in the latter. Spin dynamics probed by ac susceptibility are strongly affected by the substitution, inducing superparamagnetism at low temperature in Fe{sub 2}MnBO{sub 5}. Interestingly, for both oxyborates, glassiness is observed in the dielectric properties at low temperature, but only Fe{sub 3}BO{sub 5} shows a magnetodielectric effect close to its lower magnetic transition. A change in the electrical polarization, measured by pyroelectric current integration, is observed in Fe{sub 3}BO{sub 5} and is even more pronounced in Fe{sub 2}MnBO{sub 5}. Such results suggest that these oxyborates behave like antiferromagnetic relaxor ferroelectrics. These features are proposed to be related to the distribution of the species (Fe{sup 3+}, Fe{sup 2+} and Mn{sup 2+}) over the four transition metal sites forming the ludwigite structure. - Graphical abstract: 90 K [010] electron diffraction patterns of Fe{sub 3}BO{sub 5}. The yellow arrows in the pattern indicate the extra-spots corresponding to the superstructure induced by the charge ordering. - Highlights: • The TEM (ED) study of the Fe{sub 3}BO{sub 5} oxyborate at 90 K reveals a superstructure related to a Fe{sup 2+}/Fe{sup 3+}more » ordering. • The Fe{sub 2}MnBO{sub 5}, Mn-substituted counterpart, does not show such ordering. • Our magnetic and electric measurements demonstrate that these magnetic ferrites exhibit glassiness in their charges (relaxor-type) with additional superparamagnetism at low T for Fe{sub 2}MnBO{sub 5} and magnetodielectric coupling near T{sub N2}=72 K in Fe{sub 3}BO{sub 5}. • The pyroelectric measurements confirm the existence of a ferroelectric behavior in these antiferromagnets. Accordingly, our results open the route to the study of other large class of the M{sub 2}{sup 2+}M’{sup 3+}BO{sub 5} ludwigites and to their complex magnetism and its relationship to relaxor ferroelectricity.« less

Authors:
 [1]; ; ;  [1];  [2];  [1]
  1. Laboratoire CRISMAT, UMR 6508 CNRS/ENSICAEN/UNICAEN, 6 bd du Maréchal Juin, 14050 CAEN Cedex 4 (France)
  2. Laboratoire Léon Brillouin, UMR 12, LLB-Saclay, 91191 GIF-SUR-YVETTE Cedex (France)
Publication Date:
OSTI Identifier:
22658185
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 246; Other Information: Copyright (c) 2016 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:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BORATES; ELECTRON DIFFRACTION; EXPERIMENTAL DATA; FERROELECTRIC MATERIALS; IRON IONS; MANGANESE IONS; POLARIZATION; TEMPERATURE RANGE 0065-0273 K

Citation Formats

Maignan, A., E-mail: antoine.maignan@ensicaen.fr, Lainé, F., Guesdon, A., Malo, S., Damay, F., and Martin, C. Charge ordering and multiferroicity in Fe{sub 3}BO{sub 5} and Fe{sub 2}MnBO{sub 5} oxyborates. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2016.11.034.
Maignan, A., E-mail: antoine.maignan@ensicaen.fr, Lainé, F., Guesdon, A., Malo, S., Damay, F., & Martin, C. Charge ordering and multiferroicity in Fe{sub 3}BO{sub 5} and Fe{sub 2}MnBO{sub 5} oxyborates. United States. doi:10.1016/J.JSSC.2016.11.034.
Maignan, A., E-mail: antoine.maignan@ensicaen.fr, Lainé, F., Guesdon, A., Malo, S., Damay, F., and Martin, C. Wed . "Charge ordering and multiferroicity in Fe{sub 3}BO{sub 5} and Fe{sub 2}MnBO{sub 5} oxyborates". United States. doi:10.1016/J.JSSC.2016.11.034.
@article{osti_22658185,
title = {Charge ordering and multiferroicity in Fe{sub 3}BO{sub 5} and Fe{sub 2}MnBO{sub 5} oxyborates},
author = {Maignan, A., E-mail: antoine.maignan@ensicaen.fr and Lainé, F. and Guesdon, A. and Malo, S. and Damay, F. and Martin, C.},
abstractNote = {The comparison of Fe{sub 3}BO{sub 5} and Fe{sub 2}MnBO{sub 5} reveals that the 2Fe{sup 2+}: Fe{sup 3+} charge ordering of the former is suppressed in the latter. Spin dynamics probed by ac susceptibility are strongly affected by the substitution, inducing superparamagnetism at low temperature in Fe{sub 2}MnBO{sub 5}. Interestingly, for both oxyborates, glassiness is observed in the dielectric properties at low temperature, but only Fe{sub 3}BO{sub 5} shows a magnetodielectric effect close to its lower magnetic transition. A change in the electrical polarization, measured by pyroelectric current integration, is observed in Fe{sub 3}BO{sub 5} and is even more pronounced in Fe{sub 2}MnBO{sub 5}. Such results suggest that these oxyborates behave like antiferromagnetic relaxor ferroelectrics. These features are proposed to be related to the distribution of the species (Fe{sup 3+}, Fe{sup 2+} and Mn{sup 2+}) over the four transition metal sites forming the ludwigite structure. - Graphical abstract: 90 K [010] electron diffraction patterns of Fe{sub 3}BO{sub 5}. The yellow arrows in the pattern indicate the extra-spots corresponding to the superstructure induced by the charge ordering. - Highlights: • The TEM (ED) study of the Fe{sub 3}BO{sub 5} oxyborate at 90 K reveals a superstructure related to a Fe{sup 2+}/Fe{sup 3+} ordering. • The Fe{sub 2}MnBO{sub 5}, Mn-substituted counterpart, does not show such ordering. • Our magnetic and electric measurements demonstrate that these magnetic ferrites exhibit glassiness in their charges (relaxor-type) with additional superparamagnetism at low T for Fe{sub 2}MnBO{sub 5} and magnetodielectric coupling near T{sub N2}=72 K in Fe{sub 3}BO{sub 5}. • The pyroelectric measurements confirm the existence of a ferroelectric behavior in these antiferromagnets. Accordingly, our results open the route to the study of other large class of the M{sub 2}{sup 2+}M’{sup 3+}BO{sub 5} ludwigites and to their complex magnetism and its relationship to relaxor ferroelectricity.},
doi = {10.1016/J.JSSC.2016.11.034},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 246,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • Single crystals of new oxyborates, Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}, were prepared at 1370 deg. C in air using B{sub 2}O{sub 3} as a flux. They were colorless and transparent with block shapes. X-ray diffraction analysis of the single crystals revealed Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3} to be isostructural. The X-ray diffraction reflections were indexed to the orthorhombic Pnma (No. 62) system with a=9.3682(3) A, b=9.4344(2) A, c=9.3379(3) A and Z=4 for Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and a=9.3702(3) A, b=9.4415(3) A, c=9.3301(2) A and Z=4 for Mg{submore » 5}TaO{sub 3}(BO{sub 3}){sub 3}. The crystal structures of Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3} are novel warwickite-type superstructures having ordered arrangements of Mg and Nb/Ta atoms. Polycrystals of Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} prepared by solid state reaction at 1200 deg. C in air showed broad blue-to-green emission with a peak wavelength of 470 nm under 270 nm ultraviolet excitation at room temperature. - Graphical abstract: Single crystals of new oxyborates, Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}, were synthesized by a self flux method. They crystallize in novel warwickite-type superstructures having ordered arrangements of Mg and Nb/Ta atoms. Highlights: > Single crystals of two new oxyborates, Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} and Mg{sub 5}TaO{sub 3}(BO{sub 3}){sub 3}, were prepared using B{sub 2}O{sub 3} as a flux. > Both oxyborates crystallize in isotypic novel warwickite-type superstructures with seven-fold coordinated Nb/Ta atoms. > Polycrystalline sample of Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} was prepared by solid state reaction. > Polycrystalline Mg{sub 5}NbO{sub 3}(BO{sub 3}){sub 3} exhibits broad blue-to-green emission with a peak wavelength of 470 nm under 270-nm excitation.« less
  • A new family of lithium rare earth oxyborates of formula LiLn{sub 6}O{sub 5}(BO{sub 3}){sub 3} (Ln = Pr-Tm) has been discovered in the ternary-phase diagrams Li{sub 2}O-Ln{sub 2}O{sub 3}-B{sub 2}O{sub 3}. Since crystals of LiGd{sub 6}O{sub 5}(BO{sub 3}){sub 3} were grown by the flux method. The structure of the oxyborate was solved using a data collection with a four-circle automatic diffractometer (CAD-4) and with MoK{alpha} radiation. The cell is monoclinic (space group P2{sub 1}/c, Z = 4) with a = 8.489(4) {angstrom}, b = 15.706(3) {angstrom}, c = 12.117(6) {angstrom}, {beta} = 132.27(2){degree}, and V = 1195(1) {angstrom}{sup 3}. Refinementmore » of 198 parameters using 4402 independent reflections having intensity I > 3{sigma}(I) led to R = 0.037 (wR = 0.087). The structure of LiGd{sub 6}O{sub 5}(BO{sub 3}){sub 3} can be described as a three-dimensional framework, (Gd{sub 6}O{sub 14}){sup 10{minus}}, of Gd polyhedra connected by common edges and corners, forming cavities where Li and B atoms are inserted. Some oxygen atoms share only Gd polyhedra, justifying the oxyborate label.« less
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  • The authors have investigated the mechanism and determined the enthalpy of crystallization of x-ray amorphous iron garnets of rare-earth elements and their solid solutions. The authors have established a relation between the mechanism of the solid-phase reaction of formation of the iron garnets and the decrease in the ionic radius of the rare-earth element in the dodecahedral positions. A rise in the temperature during crystallization of amorphous phases facilitates a rapid completion of the reaction in which double oxides with a complex three-sublattice structure are released.
  • Three symmetrical mixed-valence dimers (and their oxidized and reduced congeners) have been examined in solution by Raman spectroscopy with use of near-infrared excitation (1,064 nm, Nd:YAG source). The specific systems were (2,2{prime}-bpy){sub 2}ClRu-4,4{prime}-bpy-RuCl(2,2{prime}bpy){sub 2}{sup 4+/3+/2+}, (H{sub 3}N){sub 5}Ru-4,4{prime}-bpy-Ru(NH{sub 3}){sub 5}{sup 6+/5+/4+}, and (NC){sub 5}Fe-4,4{prime}-bpy-Fe(CN){sub 5}{sup 4{minus}/5{minus}/6{minus}}. For two of the mixed-valence ions, resonance-enhanced Raman scattering is found. (For the third, the decacyano ion, extensive thermal degradation occurs.) Studies of the corresponding fully reduced ions show, however, that the enhancement effects are due not to intervalence excitation but to weakly preresonant metal-to-ligand excitation.