Neutron spin-echo studies of the structural relaxation of network liquid ZnCl at the structure factor primary peak and prepeak

Luo, P.*; Zhai, Y.*; Leao, J. B.*; Kofu, Maiko   ; Nakajima, Kenji  ; Faraone, A.*; Zhang, Y.*

Using neutron spin-echo spectroscopy, we studied the microscopic structural relaxation of a prototypical network ionic liquid ZnCl at the structure factor primary peak and prepeak. The results show that the relaxation at the primary peak is faster than the prepeak and that the activation energy is % higher. A stretched exponential relaxation is observed even at temperatures well-above the melting point . Surprisingly, the stretching exponent shows a rapid increase upon cooling, especially at the primary peak, where it changes from a stretched exponential to a simple exponential on approaching the . These results suggest that the appearance of glassy dynamics typical of the supercooled state even in the equilibrium liquid state of ZnCl as well as the difference of activation energy at the two investigated length scales are related to the formation of a network structure on cooling.