J. Phys. Soc. Jpn. 70 (2001) pp. 1986-1989 |Next Article| |Table of Contents|
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Effects of Cation Concentration on Ionic Correlations and Dynamics of a Linearly Disordered System with the Hollandite Structure
Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044
(Received March 29, 2001)
The effects of K ion concentration on ionic correlations and dynamics of a hollandite-like one-dimensional ionic conductor have been studied by the molecular dynamics method. In the K concentration range 0.6 ≤n ≤0.8, three peaks appeared in static structure factors and shifted with the variation of n. Peak positions were characterized by the two basis vectors, periods of unit separation of K ions (nc*) and the host framework (c*), which leads to an interpretation that K ions arranged with the unit separation, c/n, are perturbed by the framework potential with the period c. The low frequency mode (ca. 15 cm-1) was seen in dielectric function for 0.6 ≤n ≤0.9, which is concerned with a K ion having one of the adjacent sites occupied and the other vacant. Another mode seen around 65 cm-1 for n=0.7 and below is attributed to a local motion of a K ion whose adjacent cavities are both vacant.
©2001 The Physical Society of Japan
KEYWORDS:K-hollandite, one-dimensional ionic conductor, molecular dynamics method, ionic correlation, static structure factor, low frequency mode
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