Compositional influence on shape and position of the first sharp diffraction peak (FSDP) in silicate and germanate glasses

Abstract

Silicate and germanate glasses studied by X-Ray diffraction methods (WAXS) show characteristic features concerning the first peak of their scattering functions (FSDP: first sharp diffraction peak). Shapes and positions of the FSDPs develop systematically with composition. The shape of the FSDPS can only be described by introducing up to three peaks. We assume that the glass networks are heterogeneous in the scale of medium range order with respect to their chemistry and/or topology and these regions are mainly connected coherently.

Compositional dependence of the first sharp diffraction peaks in alkali silicate glasses: A molecular dynamics study

“…These compare well to 1.59, 1.74, and 1.77 Å À1 for silica, lithium and sodium disilicate glasses, respectively, obtained from the simulations of this work. The FSDP peak position Q 1 has been shown to be related to the characteristic repeat distance d = 2p/Q 1 in real space atomic arrangements [5,7]. Also, the FWHM is interpreted as the correlation length L = 2p/FWHM due to atomic density fluctuation [5,7].…”

“…The FSDP peak position Q 1 has been shown to be related to the characteristic repeat distance d = 2p/Q 1 in real space atomic arrangements [5,7]. Also, the FWHM is interpreted as the correlation length L = 2p/FWHM due to atomic density fluctuation [5,7]. The characteristic repeat distance and correlation length are listed in Table 3.…”

“…It has been shown experimentally that the FSDP intensity depend strongly on the glass composition [3][4][5][6][7][8]. Adding sodium or potassium oxide to silica results in a decrease of the intensity of the FSDP [4,8].…”

“…It is found that both the characteristic repeat distance and the correlation length decrease as water concentration increases [7]. In a study of compositional dependence of FSDP in multi-component silicate and germanate glasses using wide angle X-ray scattering, the position and shape of the FSDPs have been used to determine the intermediate range order of the glasses [5].…”

“…Structure features in glasses have been correlated to the position and shape of the FSDP [5,7]. The position of the FSDP (Q 1 ) is related to the atomic arrangement with characteristic repeat distance determined by 2p/Q 1 and the full width half maximum (FWHM) of FSDP is interpreted as resulting from the regions of atomic density fluctuation with a correlation length of 2p/FWHM.…”