It was proposed that monitoring the infra-red luminescence along the diffusion direction of activator ions in crystals of AgBr would be a sensitive and minimally invasive method for determining the diffusion coefficient, diffusion enthalpy, and temperature dependence of these parameters for various ions. This technique was used to study the diffusion of Nd3+. In order to establish the concentration range within which the luminescence method was useful, the dependence of the luminescence kinetics upon Nd-ion concentration was investigated. The results could be described by:

D (cm2/s) = 1.2 x 10-5 exp[-0.51(eV)/kT]

It was found that high values of the diffusion coefficient and low values of the diffusion enthalpy facilitated the preparation of high optical quality crystals.

Luminescence Method for the Study of Nd3+ Ion Diffusion in AgBr Crystals. L.Nagli, A.German, A.Katzir: Journal of Applied Physics, 1999, 85[4], 2114-8