Propriedades fotoluminescentes de nanopartículas de CaWO4 dopadas com Sm3+ e Tb3+ obtidas pelo método sonoquímico

Abstract

The tungstates have been the subject of study due to their several applications, such as lasers, sensors, catalysts, fluorescent lamps, among others. Among the tungstates, the calcium tungstate (CaWO4) have been stand out by its photoluminescent properties, which can be favored by doping. In this work, one step sonochemical method was used to get nanoparticles of Sm3+ and Tb3+ doped CaWO4. The nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and visible ultraviolet spectroscopy (UV-Vis). The photoluminescent properties measurements were made at room temperature and at lower temperatures for analysis of doping in emission color. XRD results show the formation of a scheelite structure without the presence of second phase. SEM and TEM images indicate the formation of nanospheres for pure and samarium-doped samples, while terbium doping results in the formation of nanorods. Room temperature photoluminescence spectra indicate a blue emission for the CaWO4 sample, while the samarium doping reduces this intensity and terbium doping emits at the green color. The reduction in emission temperature favors the effects of the matrix, changing the emission color to the blue/green region.