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Title: Exploring the high-pressure behavior of superhard tungsten tetraboride

In this work, we examine the high-pressure behavior of superhard material candidate WB{sub 4} using high-pressure synchrotron x-ray diffraction in a diamond anvil cell up to 58.4 GPa. The zero-pressure bulk modulus, K{sub 0}, obtained from fitting the pressure-volume data using the second-order Birch-Murnaghan equation of state is 326 {+-} 3 GPa. A reversible, discontinuous change in slope in the c/a ratio is further observed at {approx}42 GPa, suggesting that lattice softening occurs in the c direction above this pressure. This softening is not observed in other superhard transition metal borides such as ReB{sub 2} compressed to similar pressures. Speculation on the possible relationship between this softening and the orientation of boron-boron bonds in the c direction in the WB{sub 4} structure is included. Finally, the shear and Young's modulus values are calculated using an isotropic model based on the measured bulk modulus and an estimated Poisson's ratio for WB{sub 4}.
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  1. (UCLA)
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. B; Journal Volume: 85; Journal Issue: (6) ; 2012
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
National Science Foundation (NSF)
Country of Publication:
United States