Formation of XeN₄ at high pressure-high temperature conditions

Mixtures of xenon and nitrogen have been observed to form a cubic, van der Waals compound Xe(N₂)₂ at pressures above 2 GPa in concurrence with the study reported to pressures above 150 GPa [1,2]. The existence of the z phase of nitrogen [3] and hcp xenon [4] could be inferred from x-ray diffraction. The sample becomes opaque above 170 GPa and could be laser heated quite easily. In contrast to what is reported for pure N₂ [5], a new phase forms when the sample was laser heated above 2800 K and above 160 GPa. This phase is identified to be monoclinic and has distinctive Raman signatures that can be ascribed to the existence of N₄ units which are linear and double bonded. This is at variance to the theoretical prediction of cubic XeN₆ [6]. We will report the details of the spectroscopy (Raman and FTIR) as well as synchrotron powder diffraction analysis of this potentially energetic nitride of xenon.
[1] R. Howie et. al, Scientific Reports, 6, 34896 (2016).
[2] D. Laniel et al, Phys. Rev. B, 94, 174109 (2016)
[3] E. Gregoryanz et. al, Phys. Rev. B 66, 224108 (2002).
[4] H. Cynn et al, Phys. Rev. Lett. 86, 4552 (2001)
[5] D. Tomassino et. al, Phys. Rev. Lett., 113, 205502 (2014)
[6] F. Peng et. al, Phys. Rev. B, 92, 094104 (2015)