Electronic and structural origin of ultraincompressibility of 5d transition-metal diborides MB2 (M=W, re, os)
Electronic and structural origin of ultraincompressibility of 5d transition-metal diborides MB2 (M=W, re, os)
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DOI：
10.1103/physrevlett.100.196403
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发表时间：
2008-05-16
影响因子：
8.6
通讯作者：
Painter, G. S.
中科院分区：
文献类型：
--
作者：
Chen, Xing-Qiu;Fu, C. L.;Painter, G. S.
采用第一性原理理论研究了键拓扑和共价性对5d过渡金属二硼化物相稳定性和弹性强度的影响，重点研究了压缩系数最低的元素（M=W，Re，Os）.在所研究的相中，ReB2型结构具有最大的不可压缩性（c轴），与金刚石的不可压缩性相当。这种ReB2结构被预测为WB2的基态相和OsB2的压力诱导相（高于2.5 GPa）。强共价性和相互连接的键的锯齿形拓扑结构都是这些超不可压缩性的基础。有趣的是，WB2的维氏硬度估计与超硬ReB2的维氏硬度相似。
First-principles theory was used to investigate the roles of bond topology and covalency in the phase stability and elastic strength of 5d transition-metal diborides, focusing on elements (M=W, Re, Os) that have among the lowest compressibilities of all metals. Among the phases studied, the ReB2-type structure exhibits the largest incompressibility (c axis), comparable to that of diamond. This ReB2 structure is predicted to be the ground-state phase for WB2 and a pressure-induced phase (above 2.5 GPa) for OsB2. Both strong covalency and a zigzag topology of interconnected bonds underlie these ultraincompressibilities. Interestingly, the Vickers hardness of WB2 is estimated to be similar to that of superhard ReB2.