Valence transition in (Pr,Ca)CoO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>cobaltites: Charge migration at the metal-insulator transition

García-Muñoz, J. L.; Frontera, C.; Barón-González, A. J.; València, S.; Blasco, Javier; Feyerherm, R.; Dudzik, E.; Abrudan, R.; Radu, F.

doi:10.1103/physrevb.84.045104

Cited by 57 publications

(56 citation statements)

References 34 publications

(77 reference statements)

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“…For the prototypical compound Pr 0.5 Ca 0.5 CoO 3 this valence shift was confirmed and determined quantitatively with the identification of the Pr 4þ -related Schottky peak in heat capacity measurements 12 and by X-ray absorption spectroscopy at the Pr L 3 edge. 13 Similar evidence was presented also for the Pr 0.7 Ca 0.3 CoO 3 systems doped by Y, [14][15][16] Sm, 17 and Tb. 18 Many studies have been done especially on the (Pr 1Ày Y y ) 0.7 Ca 0.3 CoO 3 system, which displays a MI-SS transition and partial Pr 3þ !…”

Section: Introductionsupporting

confidence: 59%

“…This process is compensated by the valence change of some Pr 3þ ions to Pr 4þ ions; 13,15 we determined the final amount to be 0.11 Pr 4þ per f. u. based on the Schottky peak in heat capacity under ZFC (experiment to be published elsewhere). Surprisingly, we detected a certain reduced amount of Pr 4þ even after a cooling run in a 9-T field, when the MI-SS transition was suppressed and the y ¼ 0.0625 sample remained in the metallic state.…”

Section: Resultsmentioning

confidence: 99%

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Suppression of the metal-insulator transition by magnetic field in (Pr1−yYy)0.7Ca0.3CoO3 (y = 0.0625)

Naito

Fujishiro

Nishizaki

et al. 2014

Journal of Applied Physics

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The (Pr 1Ày Y y ) 0.7 Ca 0.3 CoO 3 compound (y ¼ 0.0625, T MIÀSS ¼ 40 K), at the lower limit for occurrence of the first-order metal-insulator (MI) and simultaneous spin-state (SS) transitions, has been studied using electrical resistivity and magnetization measurements in magnetic fields up to 17 T. The isothermal experiments demonstrate that the low-temperature insulating phase can be destabilized by an applied field and the metallic phase returns well below the transition temperature T MIÀSS . The reverse process with decreasing field occurs with a significant hysteresis. The temperature scans taken at fixed magnetic fields reveal a parabolic-like decrease in T MIÀSS with increasing field strength and a complete suppression of the MI-SS transition in fields above 9 T. V C 2014 AIP Publishing LLC. [http://dx

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Section: Introductionsupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Suppression of the metal-insulator transition by magnetic field in (Pr1−yYy)0.7Ca0.3CoO3 (y = 0.0625)

Naito

Fujishiro

Nishizaki

et al. 2014

Journal of Applied Physics

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“…Additionally, useful material properties such as temperature-induced metal-insulator transitions and thermoelectricity have been reported as well [4][5][6][7][8][9]. In the work presented here we study microwave (MW) -assisted synthesis of the RE cobaltites (RE)CoO3 (RE = La -Dy) series in order to demonstrate the feasibility of the MW technique for this class of materials.…”

Section: Introductionmentioning

confidence: 99%

Microwave-Assisted Synthesis, Microstructure, and Magnetic Properties of Rare-Earth Cobaltites

et al. 2016

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Citation for published item:quti¡ errez eij sD tuli nd r doEqonj lD tes¡ us nd ¡ evil fr ndeD h vid nd erryD s n nd wor¡ nD imilio nd hmidtD iner @PHIUA 9wi row veE ssisted synthesisD mi rostru tureD nd m gneti properties of r reEe rth o ltitesF9D snorg ni hemistryFD ST @IAF ppF TPUETQQF Further information on publisher's website:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Inorganic Chemistry, copyright c 2016 American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see https://doi.org/10.1021/acs.inorgchem.6b02557. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe series of perovskite rare-earth (RE) doped cobaltites (RE)CoO3 (RE = La -Dy) was prepared by microwave-assisted synthesis. The crystal structure undergoes a change of symmetry depending on the size of the RE cation. LaCoO3 is rhombohedral, S.G. , while for the rest of the RE series (Pr -Dy) the symmetry is orthorhombic, S.G. Pnma (No. 62). The crystal structure obtained by X-Ray diffraction was confirmed by high resolution transmission electron microscopy, which yielded a good match between experimental and simulated images. It is further shown that the well-known magnetism in LaCoO3, which involves a thermally induced Co 3+ (d 6 ) low spin to intermediate or high spin state transition, is strongly modified by RE-doping and a rich variety of magnetic order has been detected across the series.

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“…11,13,15 Over a temperature interval as large as HT-LT=40 K, however, one can consider that the greatest part of the valence change is completed. 11,13,15 Therefore, we adopt hereafter the approximation that [Pr 4+ ] goes from 0.13 (at LT) to 0 (at HT), allowing the analysis to be focused on the variation of [Co 3+ HS] across the transition.…”

Section: Position Of the Problemmentioning

confidence: 99%

“…[1][2][3] Starting from 2010 however, it was shown that the stabilization of a mixed Pr 3+ /Pr 4+ valence at low temperatures was also involved in this transition. 8,[9][10][11][12][13] In addition to the SST transition affecting the Co 3+ , a Pr 4+ -to-Pr 3+ transformation takes place when crossing T* upon warming, being counterbalanced by a corresponding change from Co 3+ to Co 4+ . 8,[10][11][12] The transition at T* in these compounds can thus be regarded as a coupled valence and spinstate transition (VSST).…”

Section: Introductionmentioning

confidence: 99%

Jumps in entropy and magnetic susceptibility at the valence and spin-state transition in a cobalt oxide

Hardy¹,

Guillou²,

Bréard³

2013

J. Phys.: Condens. Matter

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A wide family of cobalt oxides of formulation (Pr 1−y Ln y ) 1−x Ca x CoO 3 (Ln being a lanthanide) exhibits a coupled valence and spin-state transition (VSST) at a temperature T*, which involves two concomitant modifications: (i) a change in the spin state of Co 3+ from low-spin (T < T*) to a higher spin-state (T > T*), and (ii) a change in the valence state of Pr, from a mixed Pr 4+ /Pr 3+ state (T < T*) to a purely trivalent state (T > T*), accompanied by an equivalent charge transfer within the Co 3+ /Co 4+ subsystem. In the present paper, the VSST taking place in (Pr 0.7 Sm 0.3 ) 0.7 Ca 0.3 CoO 3 at T*  90 K is investigated by magnetization and heat capacity measurements. First , we quantitatively characterized the jumps in magnetic susceptibility () and entropy (S) around T*. Then, these values were compared to those calculated as a function of the variations in the population of the different cationic species involved in the VSST. X-ray absorption spectroscopy experiments recently showed that the higher spin state above T* should be regarded as an inhomogeneous mixture between lowspin (LS) and high-spin (HS) states. In the frame of this description, we demonstrate that the jumps in both  and S can be associated to the same change in the Co 3+ HS content around T*. This result lends further support to the relevance of the LS/HS picture for the VSST, challenging the currently dominant interpretation based on the occurrence of an intermediatespin (IS) state of Co 3+ above T*.

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Valence transition in (Pr,Ca)CoO3cobaltites: Charge migration at the metal-insulator transition

Cited by 57 publications

References 34 publications

Suppression of the metal-insulator transition by magnetic field in (Pr1−yYy)0.7Ca0.3CoO3 (y = 0.0625)

Suppression of the metal-insulator transition by magnetic field in (Pr1−yYy)0.7Ca0.3CoO3 (y = 0.0625)

Microwave-Assisted Synthesis, Microstructure, and Magnetic Properties of Rare-Earth Cobaltites

Jumps in entropy and magnetic susceptibility at the valence and spin-state transition in a cobalt oxide

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