Luminescence Study of the Thermal Decomposition of Europium Trichloride Hexahydrate, EuCl3·6H2O

Abstract

We have studied the thermal decomposition of EuCl3·6H2O using in situ measurements of the Eu3+ ion luminescence spectrum. The luminescence spectrum proved to be extremely sensitive to structural and compositional changes undergone by the title compound during the decomposition process. There appeared to be no change in the oxidation state of the europium throughout the decomposition process. Four differently hydrated species of EuCl3· nH2O ( n = 6, 3, 2, or 1) were identified via luminescence spectroscopy. We also observed another intermediate compound formed from the monohydrate prior to the final product EuOCl. Our analysis of this intermediate's spectrum indicates a single Eu3+ ion site, which is consistent with a formulation of Eu(OH)Cl2 rather than a mixed EuOCl·2EuCl3 product, both of which have been postulated by others on the basis of their thermogravimetric measurements.