title: WB2: not a superhard material for strong polarization character of interlayer W-B bonding.
abstract: In this work, the structure of WB2synthesized at high pressure and high temperature (HPHT) was accurately determined by X-ray diffraction and Rietveld refinement. Its asymptotic Vickers hardness (Hv) value is 25.5 GPa which is much lower than the previous theoretical results (36-40 GPa). It is worth noting that the chemical bonds between the W layers and two different kinds of B layers show obvious polarization character based on the results obtained from X-ray photoelectron spectroscopy (XPS) and electron localization functions (ELFs), density of states (DOS), topological analysis of the static electron density and Mulliken population. This result can well clarify that WB2is only a hard but not superhard material. Thus, a 3D network structure can not be formed between the W layers and the B layers which is previously predicted by theoretical calculations. Our results are helpful to understand the hardness mechanism and design superhard materials in TMBs.
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. zhupw@jlu.edu.cn.
authors.forename: Changchun
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. zhupw@jlu.edu.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Tao
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. zhupw@jlu.edu.cn.
authors.forename: Shuailing
authors.initials: S
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. zhupw@jlu.edu.cn.
authors.forename: Tian
authors.initials: T
authors.lastname: Cui
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. zhupw@jlu.edu.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. zhupw@jlu.edu.cn.
authors.forename: Shushan
authors.initials: S
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China. zhupw@jlu.edu.cn.
authors.forename: Pinwen
authors.initials: P
authors.lastname: Zhu