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Yamada T, Matsuo N, Enoki M, Yamane H. A novel ternary bismuthide, NaMgBi: crystal and electronic structure and electrical properties. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2021. [DOI: 10.1515/znb-2021-0130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
A new ternary sodium magnesium bismuthide, NaMgBi, has been synthesized from the constituent metals, and its crystal structure was determined by single-crystal X-ray diffraction. NaMgBi crystallizes in a tetragonal PbFCl-type structure corresponding to the space group P4/nmm, where Z = 2, a = 4.7123(4) and c = 7.8158(7) Å. The structure is composed of layers formed by edge-sharing Bi tetrahedra centered with Mg stacked in the c-axis direction, and these layers sandwich the Na atoms. First-principles computations based on density functional theory calculations have verified that the most stable atomic configuration is the one in which the Na and Mg atoms occupy the 2a and 2c sites, respectively. The electrical resistivity measured for a sintered polycrystalline sample of NaMgBi with a relative density of 70% was found to gradually decrease from 868 to 26.4 mΩ cm upon increasing the temperature from 297 to 506 K, and the Seebeck coefficient decreased from 273 to 180 μV K−1 upon increasing the temperature from 298 to 496 K. Electronic structure calculations have revealed that NaMgBi must be a semiconductor with a small band gap of ∼0.1 eV.
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Affiliation(s)
- Takahiro Yamada
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Katahira 2-1-1 Aoba-ku , Sendai 980-8577 , Japan
| | - Naoki Matsuo
- Department of Metallurgy, Materials Science and Materials Processing , Graduate School of Engineering, Tohoku University , 6-6-04 Aramaki Aza Aoba, Aoba-ku , Sendai 980-8579 , Japan
| | - Masanori Enoki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Katahira 2-1-1 Aoba-ku , Sendai 980-8577 , Japan
| | - Hisanori Yamane
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Katahira 2-1-1 Aoba-ku , Sendai 980-8577 , Japan
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