Abstract
Abstract
Based on an analysis ofelectronic structures and phonon spectra calculationsas a function of electronic temperature Te using the density functional theory, we investigated the phase stability and mechanical responseto electronic excitation effect on variousphases of tantalum nitrides TaNx with fully or partially occupied nitrogen sublattices. The results suggest that the cubic phase exhibits lattice instability at room temperature, while the hexagonal phases are dynamically stable. The phase stability increases in the sequence TaN (δ-type), TaN0.43, TaN0.5, TaN (AsNi type), TaN0.83, TaN (θ-type), and TaN (ε-type). The nonmetal vacancies exhibit enhanced latticestability with hexagonal phasescompared to the cubicphase. The electronic excitation effect providedextra stability for cubic δ-TaNwith the increase inelectronic temperature, whilethe excitation results in a lower degree of stability for hexagonal phases.The physical origin of electronic excitation effects on both the cubic and hexagonal phase stability of TaN can be attributed to the peculiarities of their electronicdensities of states near the Fermi level and a combination of three different types of bonding characteristics.The counterintuitivebehavior oflattice stabilities appears or disappears as a response to mechanical properties under electronic excitation.
Funder
the National Science Foundation of China
the National Natural Science Foundation of China
Fundamental Research Funds for the Central Universities
the National Key R&D Program of China
Subject
Metals and Alloys,Polymers and Plastics,Surfaces, Coatings and Films,Biomaterials,Electronic, Optical and Magnetic Materials
Cited by
2 articles.
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