Estudo das propriedades luminescentes de vidros Zinco Borofosfato (ZBP) Tridopados com Tm2O3, Tb4O7 E Sm2O3

Abstract

This work presents the study of zinc borophosphate glasses doped and tri-doped with Tm2O3, Tb4O7 and Sm2O3. The samples were prepared by the melt-quenching technique in air atmosphere furnaces. The samples were single-doped with Tm2O3 (0.25 mol%), Tb4O7 (0.50 mol%) and Sm2O3 (0.35 mol%), and tri-doped with different concentrations of Tm2O3 (0.25, 0.5 and 0.75 mol%). The changes in optical, luminescent, and spectroscopic properties by codoping and the possibility of energy transfer between the ions studied were investigated. The results of XRD confirmed the amorphous nature of the glasses studied. The values of the volumetric density show an increase with Tm3+ content for the tri-doped samples. The FTIR results showed that the vitreous network is formed by BO3 and BO4 structures, in addition to vibrations related to phosphate groups and ZnO4. The refractive index (n) results of the tri-doped glasses showed an increase with the insertion of dopants in the glass matrix. The absorption spectra present characteristic peaks of Tm3+, Tb3+ and Tm3+ and the increasing of Tm3+ bands intensity as a function of Tm3+ concentration. The excitation spectra of the three ions demonstrate that the wavelength of 357 nm is the most suitable for the excitation of the tri-doped samples. Under excitation at 357 nm, it was possible to produce white light by combining the blue, green and red colors emitted by the ions Tm3+, Tb3+ and Sm3+, respectively (RGB combination). Based on the CIE diagram, it was possible to obtain coordinates in the white region for all tri-doped samples, with the best result for the ZBP – 0.5TTS glass. The color rendering index (CRI) calculations showed that the ZBP – 0.5TTS sample reached the highest value (56) among the triply doped samples for this parameter, which is comparable to commercial with LEDs, which are 22 and 38. The energy transfer efficiency (η) confirmed the energy transfer process between Tm3+ and Tb3+, Tm+3 and Sm3+, and Tb3+ and Sm3+. The excited state lifetime values show a decrease with increasing Tm2O3 concentration for the concentrations of 0,25 to 0,75 mol% of Tm2O3. The results suggest that the studied glasses have potential applications in white light emitting diodes.