Sodium coordination environments in silica films

Jacques Jupille (1) , A.M. Flank , P. Lagarde

1 GPS - Groupe de Physique des Solides

The local structure centered on sodium after diffusion in silica (Na-SiO2 samples) has been determined by means of extended X-ray absorption fine structure (EXAFS) studies. The NaSiO2 samples are of particular interest because (i) their sodium content can be varied over a wide range of concentration and (ii) their local structure is representative of that of soda-silica glass. EXAFS analyses reveal the existence of a well-defined local structure involving oxygen, sodium, and silicon neighbors. The Na-O, Na-Na, and Na-Si bonds lengths, which amount to 0.23, 0.30, and 0.38 nm, respectively, do not depend on sodium concentration. This environment closely resembles that found in soda-silica glass. Moreover, it is compatible with the "target site" and "the site memory effect" suggested by recent theories of the ionic conductivity in oxide glasses.

Mots clés: bond lengths; EXAFS; Fourier transforms; glass; nuclear magnetic resonance

Jacques Jupille, A.M. Flank, P. Lagarde. Sodium coordination environments in silica films. Journal of the American Ceramic Society, 2002, 85 (5), pp.1041. ⟨10.1111/j.1151-2916.2002.tb00220.x⟩. ⟨hal-00002631⟩