Excitation energy transfer in gadolinium tantalum niobates activated with Eu3+ and Tb3+.

Series of gadolinium tantalum niobates activated with Eu3+ and Tb3+ ((Gd 1-y-z Eu y Tb z)Nb x Ta 1-x O 4 (x = 0, 0.3, 1; y = 0.6; z = 0.06; 0.15; 0.3)) were obtained for the first time. The formation of substitutional solid solutions was demonstrated. The obtained ceramic solid solutions had a monoclinic structure with I2/a space group. Electron probe microanalysis, photoluminescence (PL) and cathodoluminescence (CL) were used for studies of gadolinium tantalates and tantalum niobates series activated with Eu3++Tb3+. CL and PL spectra, concentration dependences of CL intensity and decay times, as well as excitation spectra for 5D 0 -7F 2 Eu3+ and 5D 4 -7F 5 Tb3+ bands were analyzed. It was shown for the first time that both energy transfer from Tb3+ to Eu3+ ions, and a reverse process – energy transfer from Eu3+ to Tb3+ ions are observed. This reverse process led to a decrease in CL intensity and decay times of europium bands in the presence of terbium 3+ in these materials. Presumably this phenomenon is influenced by anti-Stokes luminescence. This is confirmed by the dependences of anti-Stokes luminescence probability on temperature and excitation density. [ABSTRACT FROM AUTHOR]