Síntese e caracterização do telurato de gadolínio dopado com térbio (Gd2TeO6:Tb3+).

Abstract

The Gd2TeO6 compositions and Tb3+ ions doped Gd2TeO6 (0.5%, 1.0%, 1.5%, 2.0 and 3.0%) were obtained through solid state reaction. X-ray diffraction measurements and photoluminescence spectroscopy were performed to carry out structural and optical characterization. The resulting diffractogram for Gd2TeO6 showed an orthorhombic structure with parameters a = 5.3229 Å, b = 9.1574 Å, c = 10.0528 Å. The results showed that the compositions doped with Tb3+ also presented a single orthorhombic phase and showed a tendency towards a decrease in the lattice parameters, since the ionic radius of Tb3+ ions (1.063 Å) is slightly smaller than those of Gd3+ (1.078 Å). In the study of luminescent properties, the excitation spectra were measured with monitoring of the luminescent emission at 411nm, 488nm and 547nm. The emission ones with excitation at 312nm, 318nm, 350nm, 369nm and 377nm. The excitations at lower wavelengths were more efficient to induce emissions in the blue region (415 – 450nm), related to crystalline defects. The larger wavelengths were more efficient to excite the emissions related to Tb3+ ions (490nm= 5D4  7F6; 548nm= 5D4  7F5; 585nm= 5D4  7F4; 620nm= 5D4  7F3). The emission centered at 548nm (excitation at 369nm), characteristic of Tb3+, for the sample of Gd2TeO6: Tb3+ 3.0% presented two lifetime values 0.122ms and 1.094ms. The results showed that Gd2TeO6 is a promising matrix to host Tb3+ ions.