Effects of neodymium incorporation on the structural and luminescence properties of theYAl3(BO3)4–NdAl3(BO3)4 system

Abstract

The luminescence of Nd3+ ions in NdxY1−xAl3(BO3)4 (Nd:YAB) single crystals has been investigated as a function of the neodymiumconcentration in order to evidence the relation between the structural and spectroscopicproperties in this nonlinear laser system. The analysis of the experimental data allowed usto individuate four different composition ranges. For moderate concentrations(x<0.2) the lattice parameters are nearly constant, and the emission spectra arise fromNd3+ ions in unperturbed crystal sites. For concentrations in the0.2<x<0.75 range the lattice parameters notably depend on the neodymium content, anda concomitant variation of the luminescence features is observed. In the0.75<x<0.9 range a hexagonal to monoclinic phase transition takes place: the structuraldisorder is evidenced well by the broadening of the emission lines and bydiscontinuities in the concentration behaviour of other indicators such asthe crystal-field strength, energy transfer parameters, etc. Finally, forx>0.9 the finalformation of the NdAl3(BO3)4 (NAB) monoclinic phase is complete, and a new local ordering aroundNd3+ is very evident in the spectral features.