Jump to main content
Jump to site search

Issue 3, 2005
Previous Article Next Article

CaMn4O8, a mixed valence manganite with an original tunnel structure

Author affiliations

Abstract

A new mixed valent manganite CaMn4O8 with an original tunnel structure has been synthesized. The host lattice of this oxide has been determined by X-ray powder diffraction, using ab initio methods, and by high resolution electron microscopy. It consists of single and triple chains of edge-sharing MnO6 octahedra, interconnected through their apices. The [Mn4O8] framework delimits three types of tunnels: six-sided (“H”) and eight-sided (“8”) where sit the Ca2+ cations, and empty rutile-like tunnels (“R”). The analysis of the Mn–O inter-atomic distances shows that this structure could also be described from the association of only single chains of edge-sharing MnO6 octahedra, with single chains of edge-sharing MnO5 pyramids, and evidences a high tendency of manganese to charge ordering. Nanostructural mechanisms investigated by electron microscopy also allow the structure to be described in terms of single bricks of four Mn polyhedra, and evidence twinning and intergrowth phenomena as well as local ordering of calcium in the tunnels. The magnetic measurements show strong antiferromagnetic fluctuations at low temperature, whereas the low value of TN ∼ 90 K indicates that the antiferromagnetic superexchange is weak in this oxide.

Graphical abstract: CaMn4O8, a mixed valence manganite with an original tunnel structure

Back to tab navigation

Article information


Submitted
10 Nov 2004
Accepted
12 Nov 2004
First published
13 Dec 2004

J. Mater. Chem., 2005,15, 386-393
Article type
Paper

CaMn4O8, a mixed valence manganite with an original tunnel structure

N. Barrier, C. Michel, A. Maignan, M. Hervieu and B. Raveau, J. Mater. Chem., 2005, 15, 386
DOI: 10.1039/B417239F

Search articles by author

Spotlight

Advertisements