Frustrated and Unfrustrated Magnetic Orders in the 10H Perovskite Ba5Sb1−xMn4+xO15−δ

详细信息    查看全文

• 作者：Congling Yin ; Guobao Li ; Winfried A. Kockelmann ; Fuhui Liao ; J. Paul Attfield ; Jianhua Lin
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：May 25, 2010
• 年：2010
• 卷：22
• 期：10
• 页码：3269-3276
• 全文大小：934K
• 年卷期：v.22,no.10(May 25, 2010)
• ISSN：1520-5002

文摘

A 10-layer hexagonal perovskite Ba₅Sb_1−xMn_4+xO_15−δ solid solution (0.24 ≤ x ≤ 0.36; space group P6₃/mmc, a = 5.7095(1) Å, and c = 23.4866(3) Å for x = 0.36) has been synthesized by solid state reaction and studied using powder X-ray and neutron diffraction and magnetization measurements. This 10H polytype structure contains one corner-sharing (Sb,Mn)O₆ octahedron and a tetramer of four face-sharing MnO₆ octahedra per formula unit. Two magnetic transitions are observed at 129−167 K (T_M) and 13−22 K (T_F). The frustration index |θ|/T_M, where θ is the Weiss temperature, is very close to unity, but considerable magnetic frustration is evidenced through the long-range order of a small 0.5 μ_B antiferromagnetic moment below T_M, and the formation of ferro- or ferrimagnetic clusters. These freeze at T_F with the |θ|/T_F ≈ 7−10 index representing high magnetic frustration. T_F increases directly with the excess of Mn, x, in Ba₅Sb_1−xMn_4+xO_15−δ rather than with the overall Mn content, showing that the occupation of the corner-sharing Sb/Mn sites is key to the extended magnetism.