Matter and Radiation at Extremes (May 2021)

Pressure-induced disordering of site occupation in iron–nickel nitrides

  • Binbin Wu,
  • Li Lei,
  • Feng Zhang,
  • Qiqi Tang,
  • Shan Liu,
  • Meifang Pu,
  • Duanwei He,
  • Yuanhua Xia,
  • Leiming Fang,
  • Hiroaki Ohfuji,
  • Tetsuo Irifune

DOI
https://doi.org/10.1063/5.0040041
Journal volume & issue
Vol. 6, no. 3
pp. 038401 – 038401-9

Abstract

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Controlled disordering of substitutional and interstitial site occupation at high pressure can lead to important changes in the structural and physical properties of iron–nickel nitrides. Despite important progress that has been achieved, structural characterization of ternary Fe–Ni–N compounds remains an open problem owing to the considerable technical challenges faced by current synthetic and structural approaches for fabrication of bulk ternary nitrides. Here, iron–nickel nitride samples are synthesized as spherical-like bulk materials through a novel high-pressure solid-state metathesis reaction. By employing a wide array of techniques, namely, neutron powder diffraction, Rietveld refinement methods combined with synchrotron radiation angle-dispersive x-ray diffraction, scanning electron microscopy/energy dispersive x-ray spectroscopy, and transmission electron microscopy, we demonstrate that high-temperature and high-pressure confinement conditions favor substitutional and interstitial site disordering in ternary iron–nickel nitrides. In addition, the effects of interstitial nitrogen atoms and disorderly substituted nickel atoms on the elastic properties of the materials are discussed.