Study of Mechanism of Mixed Conduction Due to Electrons and Oxygen Ions in (La0.75Sr0.25)MnO3.00 and (Ba0.5Sr0.5)(Co0.8Fe0.2)O2.33 through Rietveld Refinement and MEM Analysis

Takanori ITOH; Saori SHIRASAKI; Yoshinori FUJIE; Naoto KITAMURA; Yasushi IDEMOTO; Keiichi OSAKA; Ichiro HIROSAWA; Naoki IGAWA

doi:10.5796/electrochemistry.77.161

Article

Study of Mechanism of Mixed Conduction Due to Electrons and Oxygen Ions in (La_0.75Sr_0.25)MnO_3.00 and (Ba_0.5Sr_0.5)(Co_0.8Fe_0.2)O_2.33 through Rietveld Refinement and MEM Analysis

Takanori ITOH, Saori SHIRASAKI, Yoshinori FUJIE, Naoto KITAMURA, Yasushi IDEMOTO, Keiichi OSAKA, Ichiro HIROSAWA, Naoki IGAWA

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Keywords: Mixed Ionic-electronic Conductor, Perovskite, Rietveld Refinement, Maximum Entropy Method, Neutron Diffraction, Synchrotron X-ray Diffraction

JOURNAL FREE ACCESS

2009 Volume 77 Issue 2 Pages 161-168

DOI https://doi.org/10.5796/electrochemistry.77.161

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Abstract

In this study, we have analyzed the mechanism of mixed conduction due to electrons and oxygen ions in (La_0.75Sr_0.25)MnO_3.00 (LSM) and (Ba_0.5Sr_0.5)(Co_0.8Fe_0.2)O_2.33 (BSCF) by using the Rietveld refinement technique and the maximum entropy method (MEM). Using neutron diffraction measurements, we showed that the site occupancies of the O1 (4c) and O2 (8d) sites in BSCF are 0.59 and 0.87, respectively. Further, the MEM analysis of synchrotron X-ray diffraction measurements revealed that the Mn-O plane in LSM has a strong, isotropic covalent bond that enables conduction of electrons. The (Co,Fe)-O2 plane with a covalent bond and a low concentration of oxygen vacancies in BSCF can also conduct electrons. On the other hand, the (Ba,Sr)-O1 plane in BSCF, which has a high concentration of oxygen vacancies, large isotropic displacement parameter (U_iso) values, and a strong ionic bond, is responsible for the diffusion of oxygen ions.

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