Pressure‐induced metallization and structural evolution of Cu₃N

Abstract

In situ resistance evolution with pressure of anti-perovskite nitride Cu 3 N was measured using the diamond anvil cell (DAC) technique up to 20.0 GPa at room temperature. A sharp drop of resistance from 105 Ω at ambient pressure to several Ω was observed in the range 3.0 -10.0 GPa. This is an indication of the pressure-induced metallization in the Cu 3 N semiconductor. Meanwhile we also performed the high-pressure energy dispersive X-ray diffraction experiments on Cu 3 N at the pressures up to 39.2 GPa. It was found that a crystal structure phase transition begins to take place at ~5.0 GPa on Cu 3 N, which is generally consistent with the electronic conductance results.

Origin of Pressure‐Induced Metallization in Cu3N: An X‐ray Absorption Spectroscopy Study

“…As one can see, a change of the spectra shape upon pressure increase is rather small, and the position of the absorption threshold remains at the same energy of ≈8982 eV (Figure b). The pressure‐dependence of the edge position at the half‐height of the normalized Cu K‐edge jump is shown in Figure : its qualitative behavior with the onset at ≈5 GPa correlates well with a transition to metal state observed in Zhao et al and Wosylus et al…”

“…We have shown recently that XAS is well suited to probe the local environment of Cu 3 N, providing detailed information on the thermal disorder and vibrational correlations . Here we present the results of the room‐temperature pressure‐dependent (up to 26.7 GPa) Cu K‐edge XAS study of Cu 3 N. Theoretical simulations of the experimental data allowed us to validate the available structural models and suggest that the metallic state in Cu 3 N is reached under high pressure because of a continuous decrease and eventual collapse of the band gap.…”

“…The Cu K‐edge XANES spectra of different Cu 3 N phases were calculated accounting for electric dipolar and quadrupolar transitions by the ab initio FDMNES code using full‐multiple‐scattering (FMS) approach (Green formalism) and a self‐consistent muffin‐tin potential. The phase structures were taken from the models reported in Zhao et al, Yu et al, Cancarevic et al, and Ghoohestani et al The real energy‐dependent exchange‐correlation correction was described by the Hedin–Lundqvist potential. The calculated XANES was broadened using the convolution with a Lorentzian to account for the core‐hole and the final state life‐time …”

“…Such crystal lattice and its low decomposition temperature (600–800 K) indicate on the possibility of the Cu 3 N structure instability under high pressure. In fact, the pressure‐induced metallization of Cu 3 N above ≈5 GPa has been observed in the past by electrical resistance and optical absorption measurements. However, its origin remains a puzzling task.…”

CVD of Copper(I) Nitride

“…[17] When the metastable Cu 3 N is heated, it decomposes into metallic copper and nitrogen gas, a behavior that could be exploited in copper metallization. [18,19] Cu 3 N is also expected to be a good host material for Li or Cu atoms, [20] since it exhibits the anti-ReO 3 structure, which is rather open with the Cu atoms occupying the midpoints of the edges and the N atoms occupying the cell corners. The experimentally measured band gap (indirect) for Cu 3 N films seems to be dependent upon the nitrogen content, and has been reported to be in the range 1.3-2.1 eV.…”