Unusual suppression of tungsten 5d electron depletion in superhard tungsten tetraboride solid solution with chromium under compression
| Autor: | Yu Gong, Haijing Li, Dongliang Chen, Zheng Dong, Juncai Dong, Zhiying Guo, Qiang Tao, Jiangwen Liao |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Journal of Physics: Condensed Matter. 34:035401 |
| ISSN: | 1361-648X 0953-8984 |
| Popis: | The lattice compressibility and deformation in superhard tungsten tetraboride (WB4) solid solution with chromium (Cr) are investigated by high-pressure x-ray diffraction and x-ray absorption fine structure (XAFS) spectroscopy up to 54 GPa. In contrast to pure WB4, the c-axis softening is effectively suppressed in W0.9Cr0.1B4, and less compressibility is shown for the a- and c-axes in the entire pressure range. Meanwhile, the white-line peak of W L3-edge XAFS in W0.9Cr0.1B4 shows an absence of the sudden intensity drop as previously observed in WB4 at ∼21 GPa, suggesting a strong inhibition of W 5d electron depletion. This phenomenon is followed by an initial increase and then decrease for the W–B bond disorder, with the magnitude greatly lower than that of WB4. Besides the apparent atomic size mismatch effect, these results imply that addition of Cr, which has the same number of valence electrons as W, can introduce an unexpected electronic structure change to strengthen the W-B bond via a modification of W vacancies and B trimers distribution in WB4 lattice. Our findings point out the great significance to precise manipulation of the intrinsic W vacancies and B trimers through different solute atoms to rational optimization of WB4 hardness. |
| Databáze: | OpenAIRE |
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