Synthesis, characterization, properties, first principles calculations, and X-ray photoelectron spectroscopy of bulk Mn5SiB2 and Fe5SiB2 ternary borides
Synthesis, characterization, properties, first principles calculations, and X-ray photoelectron spectroscopy of bulk Mn5SiB2 and Fe5SiB2 ternary borides
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DOI：
10.1016/j.jallcom.2021.161377
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发表时间：
2021-08-23
影响因子：
6.2
通讯作者：
Barsoum, Michel W.
中科院分区：
文献类型：
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作者：
ElMeligy, Tarek Aly;Kota, Sankalp;Barsoum, Michel W.
在这里，我们通过反应热压Mn、Fe、Feb、Si和B粉末，合成了完全致密的、以单相为主的层状三元过渡金属硼化物Mn5SiB2和Fe5SiB2的多晶样品。用高分辨率扫描电子显微镜对原子结构进行了成像，显示出高质量的晶体。观察到细长的条状缺陷，宽度限制在纳米以下。选区电子衍射通过离散的花纹斑点进一步突出了高质量的晶体，这是沿[001]区轴的四方晶体结构所期望的。Mn5SiB_2和Fe5SiB_2的维氏硬度值分别为12.1+/-0.4 GPA和12.7+/-0.1 GPa.Mn5SiB2和Fe5SiB2的室温电阻率分别为1.5+/-0.1和1.2+/-0.1 mU欧姆。用X射线光电子能谱测得的Mn、Fe和Si的结合能支持了这些键具有金属性质的观点。密度泛函理论(DFT)计算证实了实验观察到的两种化合物的基态都是铁磁性的。我们还用密度泛函理论预测了材料的弹性和电学性质。在这两种化合物中，费米能级的态密度都是由过渡金属的d轨道决定的。这两种材料都不容易用传统工具加工，但用锋利的钴钢钻头或电火花加工(EDM)是很容易加工的。(C)2021年爱思唯尔B.V.保留所有权利。
Herein, we synthesize fully dense, bulk, predominantly single-phase, polycrystalline samples of the layered ternary transition metal borides Mn5SiB2 and Fe5SiB2 by reactively hot-pressing Mn, Fe, FeB, Si, and B powders. The atomic structures were imaged using high-resolution scanning transmission electron mi-croscopy and revealed high-crystal quality. Elongated striped defects, confined below the nanometer in width, were observed. Selected area electron diffraction further accentuates the high-crystal quality by discrete spots of pattern, that is expected from a tetragonal crystal structure along the [001] zone axis. With Vickers hardness values of 12.1 +/- 0.4 GPa, and 12.7 +/- 0.1 GPa, for Mn5SiB2 and Fe5SiB2 respectively, these borides are relatively soft. The room temperature electrical resistivities were 1.5 +/- 0.1 and 1.2 +/- 0.1 mu Omega m, for Mn5SiB2 and Fe5SiB2, respectively. The binding energies of the Mn, Fe and Si measured by X-ray photoelectron spectroscopy bolster the idea that the bonds are quite metallic in character. Density functional theory (DFT) calculations confirm that the ground states of both compounds are ferromagnetic as observed experimentally. We also use DFT to predict the elastic and electronic properties. In both compounds, the density of states at the Fermi level are dominated by the d-orbitals of the transition metals. Neither material was readily machinable with conventional tooling, but is so with sharp cobalt steel bits or electro-discharge machining (EDM). (C) 2021 Elsevier B.V. All rights reserved.