Neutron Spin-Echo Studies of the Structural Relaxation of Network Liquid ZnCl2 at the Structure Factor Primary Peak and Prepeak

Published

January 14, 2021

Author(s)

Peng Luo, Juscelino Leao, Maiko Kofu, Kenji Nakajima, Antonio Faraone, Y. Z

Abstract

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 T_m. 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 T_m. 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.

Citation

Journal of Physical Chemistry Letters

Volume

12

Issue

1

Pub Type

Journals

Citation

Luo, P. , Leao, J. , Kofu, M. , Nakajima, K. , Faraone, A. and Z, Y. (2021), Neutron Spin-Echo Studies of the Structural Relaxation of Network Liquid ZnCl₂ at the Structure Factor Primary Peak and Prepeak, Journal of Physical Chemistry Letters (Accessed October 7, 2024)