跨越 BaFe2(PO4)2 的结构重入跃迁：二维铁磁性的影响,Journal of the American Chemical Society

当前位置： X-MOL 学术 › J. Am. Chem. Soc. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

跨越 BaFe2(PO4)2 的结构重入跃迁：二维铁磁性的影响
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2013-08-22 , DOI: 10.1021/ja404697b
Rénald David ₁ , Alain Pautrat ₂ , Dmitry Filimonov ₃ , Houria Kabbour ₁ , Hervé Vezin ₄ , Myung-Hwan Whangbo ₅ , Olivier Mentré ₁

Affiliation

BaFe2(PO4)2 最近是通过水热合成制备的，并被确定为第一个二维 (2D) Ising 铁磁氧化物，其中蜂窝层由含有高自旋 Fe(2+) 离子 (S = 2) 被 PO4 基团和 Ba(2+) 阳离子隔离。BaFe2(PO4)2 在室温下具有三角 R-3 结构，但由于 (t2g)(4)(eg)(2) 引起的 Jahn-Teller (JT) 不稳定性，在 140 K 以下采用三斜 P-1 结构）配置。对三斜晶体结构进行细化以在蜂窝层中发现明显扭曲的 Fe(2+)O6 八面体，而扭曲幅度 QJT 估计为 0.019 Å。通过 DFT 计算，JT 稳定能量估计为每个公式单位 ~7 meV。低于 ~70 K，非常接近铁磁转变温度 Tc = 65.5 K，BaFe2(PO4)2 的结构在存在显着铁磁畴的情况下恢复为三角 R-3 结构。这种罕见的重入结构转变伴随着 Fe(2+) 四极分裂的不连续变化，由穆斯堡尔光谱确定。EPR 测量显示存在远高于 Tc 的磁畴，正如铁磁 2D Ising 系统所预期的那样，并支持 BaFe2(PO4)2 的磁性是单轴的 (g⊥ = 0)。

"点击查看英文标题和摘要"

Across the Structural Re-Entrant Transition in BaFe2(PO4)2: Influence of the Two-Dimensional Ferromagnetism

BaFe2(PO4)2 was recently prepared by hydrothermal synthesis and identified as the first two-dimensional (2D) Ising ferromagnetic oxide, in which honeycomb layers made up of edge-sharing FeO6 octahedra containing high-spin Fe(2+) ions (S = 2) are isolated by PO4 groups and Ba(2+) cations. BaFe2(PO4)2 has a trigonal R-3 structure at room temperature but adopts a triclinic P-1 structure below 140 K due to the Jahn-Teller (JT) instability arising from the (t2g)(4)(eg)(2) configuration. The triclinic crystal structure was refined to find significantly distorted Fe(2+)O6 octahedra in the honeycomb layers while the distortion amplitude QJT was estimated to 0.019 Å. The JT stabilization energy is estimated to be ∼7 meV per formula unit by DFT calculations. Below ∼70 K, very close to the ferromagnetic transition temperature Tc = 65.5 K, the structure of BaFe2(PO4)2 returns to a trigonal R-3 structure in the presence of significant ferromagnetic domains. This rare re-entrant structural transition is accompanied by a discontinuous change in the quadrupolar splitting of Fe(2+), as determined by Mössbauer spectroscopy. EPR measurements show the presence of magnetic domains well above Tc , as expected for a ferromagnetic 2D Ising system, and support that the magnetism of BaFe2(PO4)2 is uniaxial (g⊥ = 0).

更新日期：2013-08-22

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南