Kinetics of nonradiative relaxation from the upper active level of neodymium in a Y3Al5O12 crystal

A theoretical analysis is used to show that the relaxation of the upper active level of neodymium in a Y₃Al₅O₁₂ crystal consists of steady ordered, steady disordered, and migration-limited stages. Various methods are used to find the energy transfer microparameters. It is shown that the differences between the values of the interaction microparameters, governed by the specific nature of the optical spectra and crystal splitting schemes (varying from one crystal to another) and also by the differences in the crystal lattice geometries, result in qualitative changes in the processes of nonradiative energy relaxation from the upper active level. A comparison of the experimental results with those found theoretically shows that they are in quantitative agreement.