AMBIPOLAR DIFFUSION IN RBAG4I5

The phenomena of silver dissolution into the RbAg4I5 are studied. The Raman scattering and luminescence with high spatial resolution are used as a tool for investigation of the process of excess silver diffusion and of saturation of RbAgI5 by silver. The diffusion profile of excess silver was investigated. The diffusion flux of excess silver from surface into the bulk is caused by the simultaneous movement of Ag+ ions and electrons, due to the charge neutrality. It was shown that the small value of electron mobility limited the process of excess silver diffusion. The ambipolar diffusion coefficient (D(amb) = (1.7 +/- 0.7) x 10(-8) cm2/s) and its temperature dependence was measured and interpreted in the framework of the model of existence of self-trapped electrons. The concentration of self-trapped electrons in RbAg4I5 was established.