English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We perform a systematic \textit{ab initio} density functional study of thesuperconductivity, electronic and phononic band structures, electron-phononcoupling and elastic constants of all four possible structures of niobiumnitride $\beta$-Nb$_2$N as well as Nb-rich $\gamma$-Nb$_4$N$_3$ and N-rich$\beta^\prime$-Nb$_4$N$_5$. First of all, we find that all four structures of$\beta$-Nb$_2$N are superconductors with superconducting transitiontemperatures ($T_c$) ranging from 0.6 K to 6.1 K, depending on the structure.This explains why previous experiments reported contradicting $T_c$ values for$\beta$-Nb$_2$N. Furthermore, both $\gamma$-Nb$_4$N$_3$ and$\beta^\prime$-Nb$_4$N$_5$ are predicted to be superconductors with rather high$T_c$ of 8.5 K and 15.3 K, respectively. Second, the calculated elasticconstants and phonon dispersion relations show that all the considered niobiumnitride structures are mechanically and dynamically stable. Moreover, thecalculated elastic moduli demonstrate that all the niobium nitrides are hardmaterials with bulk moduli and hardness being comparable to or larger than thewell-known hard sapphire. Third, the calculated band structures reveal that thenitrides possess both type I and type II Dirac nodal points and are thustopological metals. Finally, the calculated electron-phonon coupling strength,superconductivity and mechanical property of the niobium nitrides are discussedin terms of their underlying electronic structures and also Debye temperatures.The present \textit{ab initio} study thus indicates that $\beta$-Nb$_2$N,$\gamma$-Nb$_4$N$_3$ and $\beta^\prime$-Nb$_4$N$_5$ are hard superconductorswith nontrivial band topology and are promising materials for exploring exoticphenomena due to the interplay of hardness, superconductivity and nontrivialband topology.

physical review. b./physical review. b

Structure and composition tunable superconductivity, band topology and  elastic response of hard binary niobium nitrides Nb$_2$N, Nb$_4$N$_3$ and  Nb$_4$N$_5$