ZrB2: Adjusting the phase structure to improve the brittle fracture and electronic properties |
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| Affiliation: | 1. Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India;2. Vikram Sarabhai Space Centre, Indian Space Research Organization, Trivandrum, 695022, India;1. CNR-ISTEC, Institute of Science and Technology for Ceramics, Via Granarolo 64, I-48018 Faenza, Italy;2. Corrosion and Metallurgy Study Centre “Aldo Daccò”, Engineering Department, University of Ferrara, G. Saragat 1, Ferrara 44122, Italy;3. Mechanical Engineering, Chemistry and Materials Department, University of Cagliari, via Marengo 2, Cagliari 09123, Italy;4. CNR-INO, National Institute of Optics, Largo E. Fermi, 6, I-50125 Firenze, Italy |
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| Abstract: | Although ZrB2 is a promising ultrahigh-temperature ceramic, the intrinsic brittleness and low fracture toughness are the main bottlenecks. To solve these key problems, by means of first-principles calculations, we predict ZrB2 new phases, and investigate the influence of new phase on the mechanical properties and electronic properties of ZrB2. The calculated results show that two new ZrB2 phases: RuB2-type with orthorhombic structure (Pmmn, No.59) and ReB2-type with hexagonal structure (P63/mmc, No.194) are dynamical stability at the ground state. Although RuB2-type and ReB2-type structures weaken the volume deformation resistance and shear deformation resistance of ZrB2, it results in brittle-to-ductile transition due to the formation of weak Zr-B bond along the shear direction. Importantly, ReB2-type structure improves the electronic properties of ZrB2 because of the strong charge overlap between conduction band and the valence band near Fermi level (EF). Therefore, our work can open up a new clue to improve the ductility and electronic properties of ZrB2. |
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| Keywords: | Crystal structure Brittle-to-ductile transition Electronic properties First-principles calculation |
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