Hard Copper Boride with Exceptional Conductivity

Copper and boron seldom engage in reaction at ambient pressure. The few reports on copper-doped boron compounds that exist in the literature often lack definitive stoichiometry. Here, we report successful synthesis of Cu_{2-δ}B_{25} single crystals (δ∼0.03, indicating Cu understoichiometry) via a hi...

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Veröffentlicht in:Physical review letters 2024-09, Vol.133 (13), p.136301, Article 136301
Hauptverfasser: Huang, Ming-Xing, Fan, Changzeng, Xu, Bo, Hou, Jingyu, Shao, Xi, Weng, Xiao-Ji, Zhang, Xiang, Hu, Wentao, Gao, Yufei, Wang, Lin, Zhao, Zhisheng, Yang, Guochun, Zhang, Dongzhou, Wang, Yanbin, Liu, Zhongyuan, Zhou, Xiang-Feng, Tian, Yongjun
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Sprache:eng
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Zusammenfassung:Copper and boron seldom engage in reaction at ambient pressure. The few reports on copper-doped boron compounds that exist in the literature often lack definitive stoichiometry. Here, we report successful synthesis of Cu_{2-δ}B_{25} single crystals (δ∼0.03, indicating Cu understoichiometry) via a high-pressure melting method using copper and β-rhombohedral boron as precursors. Crystals thus synthesized are characterized by a tetragonal boron sublattice, within which Cu atoms are either partially or fully situated at different interstices between B_{12} icosahedra. The crystals possess a high Vickers hardness of 26.5 GPa and an unusually high electrical conductivity of 1.19×10^{5}  S/m-the highest conductivity among the icosahedron-based borides. Hall measurements reveal a notable p-n conduction type transition around 30 GPa. This transition, alongside the remarkable conductivity, is potentially modulated by the copper content and its valence states within the structure. The synthesis of Cu_{2-δ}B_{25} not only broadens the spectrum of hard materials but also opens new avenues for innovative modulation of electronic properties in boron-rich compounds, with promising technological implications.
ISSN:0031-9007
1079-7114
1079-7114
DOI:10.1103/PhysRevLett.133.136301