Estudo das propriedades fotoluminescentes do aluminato de cálcio dopado com o európio III

Abstract

Luminescent materials have been widely applied in many areas, such as illumination, movies, artificial fibers, painting, optical markers and others. Among luminous materials, aluminates have been showed its quality, even more when they are doped or codoped with rare soil, due to its great chemical and thermal stability, not forgetting its lasting luminescent property. In this paper, structural and optical behaviors of calcium aluminate doped with europium III (Ca1-xEuxAl2O4 with x = 0%, 1%, 2% and 4% mole) were studied. The formulations were synthesized through sol-gel method and calcined at 1300°C and 1500°C, with fractions of deionized water and 1, 4- butanediol (diol) on its medium of reaction. Those parameters affected the crystalline structure, and the photocatalytic and luminescent properties of each sample. The xray diffraction (XRD) indicated the obtention of the desired phase and with great crystallinity on both temperatures, but the lowest temperature indicated secondary phases formation. The scanning electron microscopy (SEM) indicated that temperature increase makes the three-dimensional morphology become more compact and with a high degree sintering. The increase in fractions of europium in the diol reactional medium made the particles present a significant reduction on its size. On photocatalytic activity, the referred addition was unsatisfactory because the samples that indicated a higher influence on dyes degradation were the base samples with 0% of diol on the reaction and 0% of europium element. The sample’s photoluminescent spectra indicated narrows and well-defined bands that are characteristics of europium element transitions. They also indicate that the increase in fraction of both dopant and diol generated a photoluminescent properties increment and a photocatalysis reduction. The increase also affects samples’ color emission. On this paper, it was possible to evaluate that the base samples presented bluish and greenish colorations, and with the increase, mainly of europium, they presented warmer colorations that went from orange to red.