Crystal Structures and Magnetic Properties of the Manganese Oxide Chlorides Sr2MnO3Cl and Sr4Mn3O8-yCl
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- 作者：Christopher S. Knee ; Alexander A. Zhukov ; and Mark T. Weller
- 刊名：Chemistry of Materials
- 出版年：2002
- 出版时间：October 2002
- 年：2002
- 卷：14
- 期：10
- 页码：4249 - 4255
- 全文大小：162K
- 年卷期：v.14,no.10(October 2002)
- ISSN：1520-5002
文摘
The crystal structures of the manganese oxide chlorides Sr2MnO3Cl and Sr4Mn3O8-yCl2have been determined from neutron powder diffraction data collected at room temperatureand at 2 K. The materials crystallize in the tetragonal space groups P4/nmm (Sr2MnO3Cl)and I4/mmm (Sr4Mn3O8-yCl2) and the structures are analogous to the n = 1 and n = 3Ruddlesden-Popper phases Sr2MnO4 and Ca4Mn3O10. Both materials contain layers ofhighly distorted Mn(III)O5Cl octahedra. Sr4Mn3O8-yCl2, in addition, has a central layer ofMnO6-
octahedra with oxygen vacancies localized within the tetragonal plane. Consequently,the average coordination of the site is reduced to a mixture of 6-fold and 5-fold and some ofthe Mn atoms adopt pyramidal coordination. The level of oxygen deficiency withinSr4Mn3O8-yCl2 y = 0.44 confirms the Mn valence is predominantly +3. Magnetic susceptibilitymeasurements indicate the onset of antiferromagnetic ordering (TAF) in the materials at 80and 90 K for Sr2MnO3Cl and Sr4Mn3O8-yCl2, respectively. Antiferromagnetic order isconfirmed by the presence of magnetic scattering in the low-temperature neutron diffractiondata. The magnetic structure of Sr2MnO3Cl has been determined, yielding an orderedmanganese moment 
z = 3.74(5) B at 2 K. In contrast, the magnetic scattering exhibited bySr4Mn3O8-yCl2 suggests a level of magnetic frustration.
octahedra with oxygen vacancies localized within the tetragonal plane. Consequently,the average coordination of the site is reduced to a mixture of 6-fold and 5-fold and some ofthe Mn atoms adopt pyramidal coordination. The level of oxygen deficiency withinSr4Mn3O8-yCl2 y = 0.44 confirms the Mn valence is predominantly +3. Magnetic susceptibilitymeasurements indicate the onset of antiferromagnetic ordering (TAF) in the materials at 80and 90 K for Sr2MnO3Cl and Sr4Mn3O8-yCl2, respectively. Antiferromagnetic order isconfirmed by the presence of magnetic scattering in the low-temperature neutron diffractiondata. The magnetic structure of Sr2MnO3Cl has been determined, yielding an orderedmanganese moment z = 3.74(5) B at 2 K. In contrast, the magnetic scattering exhibited bySr4Mn3O8-yCl2 suggests a level of magnetic frustration.