| Autor: |
Anthony K. Cheetham, Arno Knappschneider, Nathan C. George, Ram Seshadri, Barbara Albert, Sebastian Henke, Jakoah Brgoch, Jerry G. Hu, Christian Litterscheid |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
Chemistry (Weinheim an der Bergstrasse, Germany). 21(22) |
| ISSN: |
1521-3765 |
| Popis: |
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. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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