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Open Access item Valence transition in (Pr,Ca)CoO3 cobaltites: Charge migration at the metal-insulator transition

Authors:García-Muñoz, J. L.
Frontera Beccaria, Carlos
Barón-González, A. J.
Blasco, Javier
Issue Date:Jul-2011
Publisher:American Physical Society
Citation:Physical Review B 84(4): 045104 (2011)
Abstract:X-ray absorption spectroscopy measurements in Pr0.5Ca0.5CoO3 and (Pr,Y)0.55Ca0.45CoO3 compositions reveal that the valence of praseodymium ions is stable and essentially +3 (Pr [4f2]) in the metallic state, but abruptly changes when carriers localize approaching the oxidation state +4 (Pr [4f1]). This mechanism appears to be the driving force of the metal-insulator transition. The ground insulating state of Pr0.5Ca0.5CoO3 is a homogeneous Co3.5-δ state stabilized by a charge transfer from Pr to Co sites: 1/2Pr3++Co3.5→1/2Pr3+2δ+Co3.5-δ, with 2δ ≈ 0.26e-.
Description:6 páginas, 5 figuras, 1 tabla.-- PACS number(s): 71.30.+h, 75.25.Dk, 75.30.Wx, 78.70.Dm.-- et al.
Publisher version (URL):http://dx.doi.org/10.1103/PhysRevB.84.045104
E-ISSNmetadata.dc.identifier.doi = DOI:1550-235X
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(ICMA) Artículos

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