ORGANIC-INTERCALATED HALOGEN-CHROMATES(II) - LOW-DIMENSIONAL MAGNETS

被引:67
作者
BELLITTO, C [1 ]
DAY, P [1 ]
机构
[1] UCL ROYAL INST GREAT BRITAIN, LONDON W1X 4BS, ENGLAND
关键词
FERROMAGNETISM; ANTIFERROMAGNETISM; CHROMIUM; FEATURE ARTICLE;
D O I
10.1039/jm9920200265
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
Ferromagnetism in non-metallic solids is quite a rare property. In solids containing molecular building blocks it is even rarer. One strategy for preparing ionic ferromagnets is to combine a low-dimensional continuous lattice containing transition-metal ions with organic molecular ions. In this article we review the synthesis, structures and magnetic and optical properties of halogenochromate(II) salts with substituted ammonium cations. The shape of the latter has a striking influence on the bulk magnetic behaviour of the solids. Monosubstituted cations yield tetrahalogenochromates(II) with layer structures which are ferromagnets with Curie temperatures up to 60 K. On the other hand, tetramethylammonium trihalogenochromates(II) are one-dimensional antiferromagnets. The striking difference in the intensities of the visible absorption spectra of the two classes of materials can be explained by an exchange-induced electric-dipole mechanism.
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页码:265 / 271
页数:7
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