An unusual high-spin ground state of Co3+ in octahedral coordination in brownmillerite-type cobalt oxide

被引：62

作者：

Istomin, S. Ya. ^{[1
,2
]}

Tyablikov, O. A. ^{[1
,2
]}

Kazakov, S. M. ^{[1
,2
]}

Antipov, E. V. ^{[1
,2
]}

Kurbakov, A. I. ^{[3
,4
]}

Tsirlin, A. A. ^{[5
,6
]}

Hollmann, N. ^{[6
]}

Chin, Y. Y. ^{[7
]}

Lin, H. -J. ^{[7
]}

Chen, C. T. ^{[7
]}

Tanaka, A. ^{[8
]}

Tjeng, L. H. ^{[6
]}

Hu, Z. ^{[6
]}

机构：

[1] Moscow MV Lomonosov State Univ, MSU MPG Partner Grp, Moscow 117234, Russia

[2] Moscow MV Lomonosov State Univ, Dept Chem, Moscow 117234, Russia

[3] NRC Kurchatov Inst, Petersburg Nucl Phys Inst, Gatchina, Russia

[4] St Petersburg State Univ, Fac Phys, St Petersburg 198504, Russia

[5] NICPB, EE-10628 Tallinn, Estonia

[6] Max Planck Inst Chem Phys Solids, DE-01187 Dresden, Germany

[7] Natl Synchrotron Radiat Res Ctr, Hsinchu 30077, Taiwan

[8] Hiroshima Univ, ADSM, Dept Quantum Matter, Higashihiroshima 7398530, Japan

来源：

DALTON TRANSACTIONS | 2015年 / 44卷 / 23期

基金：

俄罗斯科学基金会;

关键词：

TEMPERATURE THERMAL-EXPANSION; TRANSPORT-PROPERTIES; MAGNETIC-STRUCTURE; PHASE-TRANSITIONS; CRYSTAL;

D O I：

10.1039/c4dt03670k

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

The crystal and magnetic structures of brownmillerite-like Sr2Co1.2Ga0.8O5 with a stable Co3+ oxidation state at both octahedral and tetrahedral sites are refined using neutron powder diffraction data collected at 2 K (S. G. Icmm, a = 5.6148(6) angstrom, b = 15.702(2) angstrom, c = 5.4543(6) angstrom; R-wp = 0.0339, R-p = 0.0443, chi(2) = 0.775). The very large tetragonal distortion of Co-O-6 octahedra (1.9591(4) angstrom for Co-O-eq and 2.257(6) angstrom for Co-O-ax) could be beneficial for the stabilization of the long-sought intermediate-spin state of Co3+ in perovskite-type oxides. However, the large magnetic moment of octahedral Co3+ (3.82(7)mu(B)) indicates the conventional high-spin state of Co3+ ions, which is further supported by the results of a combined theoretical and experimental soft X-ray absorption spectroscopy study at the Co-L-2,L-3 edges on Sr2Co1.2Ga0.8O5. A high-spin ground state of Co3+ in Sr2Co1.2Ga0.8O5 resulted in much lower in comparison with a LaCoO3 linear thermal expansion coefficient of 13.1 ppm K-1 (298-1073 K) determined from high-temperature X-ray powder diffraction data collected in air.

引用

页码：10708 / 10713

页数：6

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