Nanocerâmicas transparentes e funcionais: síntese, caracterização e fabricação de materiais transparentes baseados em granada-ítrio-alumínio e lantanídeos similares

Abstract

This research is motivated by the production of yttrium–aluminum garnet (YAG), a transparent ceramic with a cubic crystalline structure that exhibits technologically relevant applications, such as solid-state lasers used in medicine, military defense, and industry. When doped with cerium (III) atoms, it is employed as an X-ray scintillator, serving as a detector in the Sirius beam-lines located at the CNPEM campus in Campinas (SP). Based on a selected article from the literature, a detailed study of the conditions of the co-precipitation synthesis method was conducted with the aim of improving the production of the material (powders and pellets). After obtaining a single-phase system, this knowledge was extended to advance the fabrication of other garnets, such as lutetium–aluminum garnet (LuAG) — employed as a scintillator for high-energy X-rays — and terbium–aluminum garnet (TAG), used as a matrix in various optical–magnetic devices. The powders obtained were analyzed by X-ray diffraction (XRD), and the results indicated the achievement of a pure phase after calcination at 1100 °C for 3 hours. Transmission electron microscopy (TEM) analyses provided essential in-formation regarding the particle size and morphology, revealing an average diameter of approximately 43 nm and faceted structures at the same temper-ature. Upon examining the XRD data of the produced pellet, a secondary phase was identified in the initial materials, and its nature was confirmed by additional investigations using scanning electron microscopy (SEM). Subse-quently, the analysis of the calcined powder by TEM corroborated the presence of a secondary alumina phase on its surface. Adjustments were implemented in the synthesis process to optimize the dispersion of both the pre-cipitate and the powder. At the conclusion of the research, it was possible to resolve the formation of the secondary phase, achieving single phase materials as confirmed by the XRD and SEM analyses.