Unravelling the Structure and Strength of the Highest Boride of Tungsten WB4.2
Physical Review B
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Tungsten tetraboride is outstanding among transition-metal light-element compounds for its easy synthesis and superior mechanical properties. Its crystal structure, however, has eluded scientists for over half a century, impeding fundamental understanding and rational property optimization. Recent x-ray and neutron diffraction studies suggest rare boron trimers occupying vacant metal sites in the highest boride of tungsten WB4.2, but a viable crystal structure and key mechanical properties remain unresolved. Here we identify a WB4.2 phase in orthorhombic symmetry with a very large 104-atom unit cell using a tailored search algorithm treating boron trimer as a coherent unit. First-principles studies establish phase stability and unveil the mechanism for strength enhancement by newly identified bonding features. These findings solve a challenging crystal structure and elucidate its benchmark mechanical behaviors. This work offers powerful insights for exploring novel structures and properties of materials containing intricate multiatomic constituent structural units.
Condensed Matter Physics | Physical Sciences and Mathematics | Physics
Unravelling the Structure and Strength of the Highest Boride of Tungsten WB4.2.
Physical Review B, 100(22),