Luminescence of Sm 3+ in BaTiO 3 matrix

Abstract

The luminescent emission of Sm 3+ embedded in specially purified BaTiO 3 was investigated in detail. The investigation of the dependence of the emission spectra on temperature and on samarium concentration, together with the already known assignment for the transitions responsible for Sm 3+ emission, suggests that there exist two kinds of Sm 3+ center. The effect of the introduction of some foreign cations, as well as the comparison of the Sm 3+ emission in other oxides and sulfides, leads to the conclusion that the two kinds of the Sm 3+ center are those at Ti 4+ and at Ba 2+ sites, and that the spectrum from the former center is located at longer wavelength than that from the latter center. The models for these two centers are presented and some relations between the luminescence and ferroelectricity are discussed. Temperature changes of the d.c. electric conductivity were measured. A relationship between the emission intensities and the temperature changes of conductivity was found.