Dynamics of Sodium in Sodium Disilicate: Channel Relaxation and Sodium Diffusion
Abstract
We use moleculardynamics computer simulations to study the dynamics of amorphous (Na_{2}O)2(SiO_{2}). We find that the Na ions move in channels embedded in a SiO_{2} matrix. The characteristic distance between these channels gives rise to a prepeak in the structure factor at q~0.95 Å^{1}. The dynamics of sodium is given by a fast process which can be seen in the incoherent scattering function and a slow process which is seen in the coherent function. The relaxation time of the latter coincides with the αrelaxation time of the matrix. The Kohlrausch exponent of the fast process for q>1.6 Å^{1} is the same as the von Schweidler exponent for the slow one. Thus the two processes are closely related.
 Publication:

Physical Review Letters
 Pub Date:
 March 2002
 DOI:
 10.1103/PhysRevLett.88.125502
 arXiv:
 arXiv:condmat/0110325
 Bibcode:
 2002PhRvL..88l5502H
 Keywords:

 Condensed Matter  Statistical Mechanics
 EPrint:
 9 pages, 4 figures