Formation probability of Cr-Nd pair and energy transfer from Cr to Nd in Y 3Al 5O 12 ceramics codoped with Nd and Cr

Abstract

Temperature dependence of decay curves of the Cr 3+ and Nd 3+ luminescence excited at 432 nm in the Cr 3+ absorption bands for YAG ceramics codoped with 1 mol. Nd 3+ and 0.1 mol. Cr 3+ indicates two distinct energy transfer processes from Cr 3+ to Nd 3: one is a temperature-independent process via the lowest 2E excited state of Cr 3+ through the exchange interaction between Cr 3 and Nd 3+ ions; the other is a temperature-dependent process via the higher 4T 2 excited states of Cr 3+ through the thermal Boltzmann distribution. In order to explain these results, we have proposed a simple model on energy transfer from Cr 3+ to Nd 3+, taking into account a formation probability of a Cr-Nd pair in YAG as a function of separation distance. This Cr-Nd pair model has estimated that the former and latter energy transfer processes occur from a Cr 3+ ion to one of Nd 3+ ions substituting for the first nearest neighbor Y 3+ ions and near Y 3+ ions beyond within a sphere with an approximate radius of less than 0.8 nm, respectively. © 2012 American Institute of Physics.