Exploring Hardness and the Distorted sp2 Hybridization of B鈥揃 Bonds in WB3

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• 作者：Qiang Tao ; Dafang Zheng ; Xueping Zhao ; Yanli Chen ; Quan Li ; Qian Li ; Changchun Wang ; Tian Cui ; Yanming Ma ; Xin Wang ; Pinwen Zhu
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：September 23, 2014
• 年：2014
• 卷：26
• 期：18
• 页码：5297-5302
• 全文大小：438K
• ISSN：1520-5002

文摘

In this work, tungsten triboride (WB₃) was successfully synthesized at high pressure and high temperature. The structure was reconfirmed to be WB₃ (P6₃mmc), and some part has a tungsten atomic defect according to the measurement results of X-ray diffraction, high-resolution transmission electron microscopy, and Rietveld refinement. The asymptotic Vickers hardness that had eliminated influence of excess boron is 25.5 GPa for WB₃. This value is in good agreement with the previous theoretic results. Proof of novel electron transfer between the tungsten atom and the boron atom was found. A deficient amount of transfer electron induces distorted sp² hybridization of B鈥揃 bonds in WB₃. The weakly directional sp² hybridization of B鈥揃 bonds is an essential factor that can influence the hardness of WB₃. Our results are helpful to design new hard and superhard materials of transition metal borides.