Crystal structure and high temperature X-ray diffraction study of thermoelectric chimney-ladder FeGe (γ ≈ 1.52)
作者:Sylvain Le Tonquesse、Christopher Hassam、Yuichi Michiue、Yoshitaka Matsushita、Mathieu Pasturel、Takao Mori、Tohru S. Suzuki、David Berthebaud
DOI:10.1016/j.jallcom.2020.155696
日期:2020.12
Abstract The crystal structure of Nowotny chimney-ladder phase FeGeγ with γ ≈ 1.52 was studied by X-ray diffractometry from 300 K to 850 K. The diffraction patterns were fitted by Rietveld refinement considering an incommensurate composite crystal structure. The refined crystal structure of FeGeγ is described in details and compared to MnSiγ, a thermoelectric material with γ ≈ 1.74. The lattice parameters
A series of compounds with compositions Fe5Si1-xGexB2 were synthesised and their structural and magneticproperties were investigated. The Mo5SiB2-type structure with tetragonal I4/mcm space group is maintained for all compounds with x<0.15, which is estimated as the compositional limit of the system. The unit cell parameters expand with Ge content before reaching a plateau of a = 5.5581(1) and c = 10
合成了一系列成分为Fe 5 Si 1-x Ge x B 2的化合物,并研究了它们的结构和磁性。具有四方I 4 / mcm空间群的Mo 5 SiB 2型结构对于所有具有X<0.15, 估计为系统的组成极限。晶胞参数在达到 a = 5.5581(1) 和 c = 10.3545(1) Å 的平台之前随 Ge含量 扩展X=0.15. 饱和磁化强度(米小号) 随着 Ge 含量的增加略有下降,而磁晶各向异性能量 (MAE) 几乎不受影响。所研究的所有化合物的居里温度为 790 K,而自旋重定向温度显示抑制从 172 K 到 101 K,其中X=0.15. Ab Initio计算显示,组合物的 MAE 增加X=相对于母体化合物 Fe 5 SiB 2,假设化合物 Fe 5 GeB 2的 MAE 为 0.25 且 MAE 的幅度降低了 -0.14 MJ/m 3。
Crystal Growth of the Nowotny Chimney Ladder Phase Fe<sub>2</sub>Ge<sub>3</sub>: Exploring New Fe-Based Narrow-Gap Semiconductor with Promising Thermoelectric Performance
作者:Valeriy Yu. Verchenko、Zheng Wei、Alexander A. Tsirlin、Carolien Callaert、Anton Jesche、Joke Hadermann、Evgeny V. Dikarev、Andrei V. Shevelkov
DOI:10.1021/acs.chemmater.7b03300
日期:2017.12.12
microstructure. In compliance with the 18-n electron counting rule formulated for T–E intermetallics, electronic structure calculations reveal a narrow-gap semiconducting behavior of Fe2Ge3 favorable for high thermoelectric performance. Measurements of transport and thermoelectric properties performed on the polycrystalline samples confirm the formation of a narrow band gap of ∼30 meV and reveal high absolute
引入了一种基于化学迁移反应的新合成方法,以获得单晶和多晶粉末形式的Nowotny烟囱阶梯相Fe 2 Ge 3。与以复杂的微结构为特征的多晶样品相反,单晶具有Ru 2 Sn 3型的化学计量组成和相称的烟囱阶梯结构。根据为T–E金属间化合物制定的18- n电子计数规则,电子结构计算显示Fe 2 Ge 3的窄间隙半导体行为有利于高热电性能。对多晶样品进行的输运和热电性能测量结果证实了约30 meV的窄带隙的形成,并揭示了高温下塞贝克系数的高绝对值。在较宽的温度范围内观察到较低的类玻璃热导率,这可能是由潜在的复杂微结构引起的。
Ferromagnetism in Fe-doped Ba6Ge25 chiral clathrate
作者:Yang Li、Joseph H. Ross
DOI:10.1063/1.1616658
日期:2003.10.6
We have synthesized a Ba6Ge25clathrate, substituting 3 Ge per formula unit by Fe. This chiralclathrate has Ge sites forming a framework of closed cages and helical tunnel networks. Fe atoms randomly occupy these sites, and exhibit high-spin magnetic moments. A ferromagnetic transition is observed with Tc=170 K, the highest observed Tc for a magnetic clathrate. However, the magnetic phase is significantly
我们已经合成了 Ba6Ge25 包合物,用 Fe 代替每个分子式单位 3 Ge。这种手性包合物具有形成封闭笼和螺旋隧道网络框架的 Ge 位点。Fe 原子随机占据这些位置,并表现出高自旋磁矩。观察到铁磁转变,Tc=170 K,这是磁性包合物观察到的最高 Tc。然而,磁性相显着无序,并表现出向重入自旋玻璃相的转变。该系统与其他稀磁性半导体具有许多共同特征。
The 57Fe Mössbauer isomer shift in intermetallic compounds of iron