While Li3N is often discussed as an archetypal superionic conductor, the existence of a well-defined superionic transition has not been demonstrated. Previous Xray diffraction data, however, may indicate a superionic transition within the temperature range of 588 K < T s ≤ 678 K . Across this temperature range, the ionic conductivity increases continuously , which would be indicative of a type-II superionic transition. X-ray data from Schulz and Thiemann suggests that the superionic transition would be driven by the increasing amplitude of strongly-directional anharmonic vibrations between Li(2) sites, and that these anharmonic vibrations would also promote diffusion in the superionic phase .