Neutron Spin-Echo Studies of the Structural Relaxation of Network Liquid ZnCl2 at the Structure Factor Primary Peak and Prepeak
Peng Luo, Juscelino Leao, Maiko Kofu, Kenji Nakajima, Antonio Faraone, Y. Z
Using neutron spin-echo spectroscopy, we studied the microscopic structural relaxation of liquid ZnCl2 in the temperature range from 600 K to 735 K, at wavevector transfer Q = 2.1 angstrom}−1 corresponding to the nearest-neighboring ionic correlation and Q = 1.0 angstrom}−1 associated with the intermediate range ordering. The results show that the relaxation at 2.1 angstrom}−1 is faster than at 1.0 angstrom}−1, with ≅33% higher activation energy. Nonexponential relaxation is observed even at temperatures well above the melting point Tm. Surprisingly, when the data are analyzed using a stretched exponential, the stretching exponent shows a rapid increase on cooling, especially at Q = 2.1 angstrom}−1, where it changes from stretched exponential to simple exponential on approaching Tm. Comparing the relaxation time with previous data suggests the decoupling of the fast and the slow relaxation processes. These results suggest that the appearance of glassy dynamics typical of the supercooled state even for liquid ZnCl2 as well as the difference of activation energy at the two investigated lengthscales are related to the formation of network structure on cooling.
, Leao, J.
, Kofu, M.
, Nakajima, K.
, Faraone, A.
and Z, Y.
Neutron Spin-Echo Studies of the Structural Relaxation of Network Liquid ZnCl<sub>2</sub> at the Structure Factor Primary Peak and Prepeak, Journal of Physical Chemistry Letters
(Accessed July 4, 2022)