Solubility of fluid helium in solid nitrogen at high pressure

Experiments carried out at high pressures show that the transition of completely ordered solid {ε}-N₂ to orientationally disordered {δ}-N₂ is shifted over a factor of 2 in temperature or pressure due to the admixture of fluid helium. Between 5.4 and 11.0 mole % helium can be dissolved in {ε}-N₂, favoring the occurrence of this ordered phase. In contrast, the transition from disordered {δ}-N₂ to disordered {β}-N₂ is not shifted at all.