Synthesis and Properties of Layered-Structured Mn5O8 Nanorods

被引:101
作者
Gao, Tao [1 ,2 ]
Norby, Poul [3 ]
Krumeich, Frank [4 ]
Okamoto, Hiroshi [1 ,2 ]
Nesper, Reinhard [4 ]
Fjellvag, Helmer [1 ,2 ]
机构
[1] Univ Oslo, Ctr Mat Sci & Nanotechnol, N-0315 Oslo, Norway
[2] Univ Oslo, Dept Chem, N-0315 Oslo, Norway
[3] Tech Univ Denmark, Riso Natl Lab Sustainable Energy, Mat Res Div, DK-4000 Roskilde, Denmark
[4] ETH, Inorgan Chem Lab, CH-8093 Zurich, Switzerland
关键词
SYSTEM MN-O; MANGANESE OXIDES; RAMAN-SPECTROSCOPY; LITHIUM BATTERIES; MN3O4; STABILITY; SIZE; MICROSTRUCTURES; TRANSITION; OXIDATION;
D O I
10.1021/jp9097606
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Mn5O8 nanorods were prepared by a topotactic conversion of gamma-MnOOH nanorod precursors in nitrogen at 400 degrees C. The as-prepared Mn5O8 nanorods crystallized in a monoclinic structure (space group C2/m) with unit cell dimensions a = 10.3784(2) angstrom, b = 5.7337(7) angstrom, c = 4.8668(6) angstrom, and beta = 109.491(6)degrees, having a compositional formula Mn22+Mn34+O8. The structure allowed 18 Raman-active modes (10 A(g) + 8 B-g); 10 of these contributions were observed at 262, 300, 391, 429, 475, 533, 576, 615, 647, and 789 cm(-1). An intensive A(g) mode at 647 cm(-1) was identified, representing a clear signature for probing the Mn5O8 materials via Raman scattering. X-ray photoelectron spectroscopy studies revealed the distinctive spectral features of the Mn5O8 due to the coexistence of divalent and tetravalent Mn ions. Magnetic measurements confirmed further that Mn5O8 was a mixed valence oxide with an antiferromagnetic transition at about 133 K. The decreased Neel temperature of the Mn5O8 nanorods Suggested the possible presence of the finite size effect, which accounted also for the red-shift of the corresponding Raman bands in comparison with those of the bulk counterparts.
引用
收藏
页码:922 / 928
页数:7
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