CHANGING DEBYE-WALLER FACTORS IN MIXED-ALKALI KXCS(1-X)SI2O5 GLASSES

Alkali X-ray absorption fine structure (XAFS) spectra from KxCs(1-x)Si 2O5 glasses measured at room temperature reveal changes in the Debye-W aller factors of nearest neighbour oxygen shells as the mixed alkali c omposition is altered. The thermal contributions have been estimated u sing the correlated Einstein model from the different frequencies of t he alkali vibrations in the far infrared. By comparing these with the changing Debye-Waller factors measured from XAFS, the contribution due to modifications in structural disorder around each of the alkalis is assessed. (C) 1998 Elsevier Science B.V. All rights reserved.