Estudo do campo cristalino em oxihaletos dopados com íons Eu3+

Abstract

In this work we applied to a series of oxyhalides crystals, namely, GdOBr, LaOI, GdOCl, LaOCl, YOCl and LaOBr, all doped ion Eu3 +, the point charge electrostatic model (PCEM), the simple overlap model (SOM) and method of equivalent nearest neighbors (MENN), with the objective of discussing the magnitude of the charges of the ions in this halogens series. Using the local structure of luminescent site, calculations were made of the crystal field parameters and splitting of the 7F1 level. The point charge electrostatic model, as expected, led to satisfactory predictions only from the qualitative point of view. The simple overlap model and the method gave satisfactory predictions to all quantities uce the experimental splitting energy level 7F1. It is shown that the effect of O2- ions is dominant in the calculation of crystal field parameters and charge factors of the halogens has been always smaller than those of O2- ions, although in some cases the NN charge factors was greater than the their valence, when the SOM is applied. This is not completely understood up to now.