Estudo espectroscópico de Cristais Eu3+:TR2O2S (TR=Y, La, Gd, Lu) através de modelos de campo cristalino

Abstract

In this paper we present a study of the energy position and splitting of the 7F1 and 5D1 mutiplets of the Eu3+ ion in the TR2O2S (TR = La, Gd, Y and Lu) compounds. Three models were used, namely, the point charge electrostatic model, the simple overlap model and the method of equivalent nearest neighbours. Using the coordinates of the luminescent- site, predictions of the crystal field parameters and the crystal field strength parameter and position and splitting of energy levels were performed. The electrostatic model presented good predictions only from a qualitative point of view, as expected. The same behaviour was observed when using the simple overlay model, if the charge factors entered are equal to the valence of the nearest neighbours. Using the method and a phenomenological fitting of the charge factors, in addition to satisfactorily reproduction of the data in the literature, it was observed that the dependency charge factor versus distance follows the model of Malta et al 2000, and shows increase or decrease according to the signal of the BB02parameter.