Low‐Frequency Light Scattering in Superionic Glasses (AgI)_x (Ag₂O1B₂O₃)_1−x

Abstract

Light scattering measurements are made on superionic glasses (AgI),(Ag,0nB,03)1 -% from 2 to 400 cm-1 and in the temperature range 80 to 400 K. The data show the existence of a strong low frequency scattering which has a Lorentzian shape centered a t zero frequency. A model is adopted from disordered crystals which treats such scattering as being due to the jumping of Ag ions. The fitting parameters are related to the probability of jump of the diffusing particles in various sites. An order of magnitude calculation relates the quantities obtained by the model with the completely independent measurements of conductivity and tracer diffusion ; satisfactory agreement is found.En cet article on presente des mesures de diffusion de la lumibre sur des verres superioniques de la famille (AgI),(Ag,OnB,O,)~-, dans l'interval de frequences 2 ?A 400 cm-I a plusibres temperatures entre 80 et 400 K. Les donnkes montrent l'existence aux basses frequences d'une considerable diffusion, qui a la forme d'une lorentziane centrhe a la frequence nulle. A l'aide d'un model valable pour les cristaux dbsordonnes on traite cette diffusion par rapport a la migration par sauts des ions Ag parmi le different5 endroits a l'interieur de la matrice vitreuse. Un calcul approxime a l'ordre de grandeur permit de mettre en correlation les quantitks obtenues par le model avec les resultats des mesures de conductivith ionique de diffusion des tracants radioactifs. L'accord est satisfaisant.

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