Enhancing the photoluminescence and thermoluminescence emission of cyanuric acid with Eu3+ dopant for UV radiation detection

Abstract This work reports the luminescent, thermoluminescent and morphological properties of cianuric acid (CYA) with and without Eu dopant. This material was prepared by a facile combustion method. When the CYA is doped with Eu, an organic Eu complex is formed. Three samples were doped with 0.1, 1 and 5 mol% of Eu. According to the analysis by X-ray diffraction, all the samples presented a stable hexagonal phase. The morphological analysis by scanning electron microscopy (SEM) indicated the presence of irregular microparticles in the sample without Eu dopant. However, the introduction of Eu dopant with concentrations from 0.1 to 5 mol% changed the morphology from microplates to microrods. The luminescence analysis revealed that the CYA sample without Eu dopant presented a strong blue emission band centered at 423 nm under UV excitation (370 nm), which resulted from optical transitions in the n–π*, π–π* ligands. Under the same UV excitation, the samples doped with Eu presented blue and orange-red emission bands related with Eu2+ and Eu3+ transitions. In addition, the introduction of the Eu dopant favored the creation of oxygen vacancies (trap centers), this in turn, benefited the TL properties (after UV light exposure at 254 nm) and increased the fading times. Since this new organic Eu compound presented TL properties not previously observed in Eu doped organic systems, this work opens the possibility for the development of a new class of organic TL materials for UV sensing applications.