Structure of ZnCl2 Melt. Part I: Raman Spectroscopy Analysis Driven by Ab Initio Methods

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• 作者：Abduljabar Q. Alsayoud ; Manga Venkateswara Rao ; Angharad N. Edwards ; Pierre A. Deymier ; Krishna Muralidharan ; B. G. Potter Jr. ; Keith Runge ; Pierre Lucas
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：May 5, 2016
• 年：2016
• 卷：120
• 期：17
• 页码：4174-4181
• 全文大小：421K
• 年卷期：0
• ISSN：1520-5207

文摘

The structure of molten ZnCl₂ is investigated using a combination of computer simulation and experimental methods. Ab initio molecular dynamics (AIMD) is used to model the structure of ZnCl₂ at 600 K. The structure factors and pair distribution functions derived from AIMD show a good match with those previously measured by neutron diffraction (ND). In addition, Raman spectroscopy is used to investigate the structure of liquid ZnCl₂ and identify the relative fractions of constituent structural units. To ascertain the assignment of each Raman mode, a series of ZnCl₂ crystalline prototypes are modeled and the corresponding Raman modes are derived by first-principles calculations. Curve fitting of experimental Raman spectra using these mode assignments shows excellent agreement with both AIMD and ND. These results confirm the presence of significant fractions of edge-sharing tetrahedra in liquid ZnCl₂. The presence of these structural motifs has significant impact on the fragility of this tetrahedral glass-forming liquid. The assignment of Raman bands present in molten ZnCl₂ is revised and discussed in view of these results.