Bond length compressibility in hard ReB2 investigated by x-ray absorption under high pressure
Bond length compressibility in hard ReB2 investigated by x-ray absorption under high pressure
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DOI：
10.1088/0953-8984/22/4/045701
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
J. Pellicer-Porres;A. Segura;Alfonso Muñoz;A. Polian;A. Congeduti
中科院分区：
文献类型：
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作者：
J. Pellicer-Porres;A. Segura;Alfonso Muñoz;A. Polian;A. Congeduti
这项工作描述了 ReB2 高压下的 X 射线吸收测量，并辅以从头计算。 EXAFS 分析得出平均 Re-B 键压缩率，结果为 χReB = 5.6(9) × 10−4 GPa−1。将此信息与之前的 X 射线衍射实验相结合，我们对负责结构刚性的共价键网络进行了表征。主要结论是压缩是各向异性和非均匀的，反映了Re-B键和B-B键之间以及非等价Re-B键之间的键合差异。由硼原子限定的层在高压下往往变得更平坦。结果，获得高硬度值所需的结构刚度受到损害。
This work describes x-ray absorption measurements under high pressure in ReB2, complemented by ab initio calculations. The EXAFS analysis yields the average Re–B bond compressibility, which turns out to be χReB = 5.6(9) × 10−4 GPa−1. Combining this information with previous x-ray diffraction experiments we have characterized the network of covalent bonds responsible for the rigidity of the structure. The main conclusion is that the compression is anisotropic and nonhomogeneous, reflecting bonding differences between Re–B and B–B bonds and also between nonequivalent Re–B bonds. The layer defined by boron atoms tends to become flatter under high pressure. As a consequence, the structural rigidity, necessary to attain high hardness values, is compromised.