四硼化锰（MnB₄）：高温晶体结构、p-n 转变、（55）Mn 核磁共振光谱、固溶体及力学性能
Manganese Tetraboride, MnB4: High-Temperature Crystal Structure, p-n Transition, (55)Mn NMR Spectroscopy, Solid Solutions, and Mechanical Properties.
作者信息
Knappschneider Arno, Litterscheid Christian, Brgoch Jakoah, George Nathan C, Henke Sebastian, Cheetham Anthony K, Hu Jerry G, Seshadri Ram, Albert Barbara
机构信息
Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technische Universität Darmstadt, Alarich-Weiss-Strasse 12, 64287 Darmstadt (Germany).
present address: Chemische Fabrik Budenheim KG, Rheinstrasse 27, 55257 Budenheim (Germany).
出版信息
Chemistry. 2015 May 26;21(22):8177-81. doi: 10.1002/chem.201406631. Epub 2015 Apr 17.
The structural and electronic properties of MnB4 were studied by high-temperature powder X-ray diffraction and measurements of the conductivity and Seebeck coefficient on spark-plasma-sintered samples. A transition from the room-temperature monoclinic structure (space group P2(1)/c) to a high-temperature orthorhombic structure (space group Pnnm) was observed at about 650 K. The material remained semiconducting after the transition, but its behavior changed from p-type to n-type. (55)Mn NMR measurements revealed an isotropic chemical shift of -1315 ppm, confirming an oxidation state of Mn close to I. Solid solutions of Cr(1-x)Mn(x)B4 (two phases in space groups Pnnm and P2(1)/c) were synthesized for the first time. In addition, nanoindentation studies yielded values of (496±26) and (25.3±1.7) GPa for the Young's modulus and hardness, respectively, compared to values of 530 and 37 GPa obtained by DFT calculations.
通过高温粉末X射线衍射以及对火花等离子烧结样品的电导率和塞贝克系数的测量，研究了MnB₄的结构和电子性质。在约650 K时观察到从室温单斜结构（空间群P2(1)/c）到高温正交结构（空间群Pnnm）的转变。转变后该材料仍为半导体，但其行为从p型变为n型。(55)Mn NMR测量显示各向同性化学位移为-1315 ppm，证实Mn的氧化态接近I。首次合成了Cr(1-x)Mn(x)B₄的固溶体（空间群Pnnm和P2(1)/c中的两相）。此外，纳米压痕研究得出杨氏模量值为(496±26) GPa，硬度值为(25.3±1.7) GPa，相比之下，通过DFT计算得到的值分别为530和37 GPa。
Zotero 插件