Influence of Sintering Temperature on the Structure of the Yttrium Based Phosphor Nanoparticles

Résumé

Yttrium-based phosphor materials belonging to the class known as garnets have witnessed a strong return with the development of the first white LEDs. Among these materials, yttrium aluminum garnet doped with cerium has become the best known, being successfully used in generating white light, due to its capacity to convert the blue light emitted by a GaN chip. But its use in optoelectronic applications is subject to the achievement of parameters such as: purity of the crystal phase and particles size in the nanoscale range. In this study, we present a modified sol-gel method for the synthesis of yttrium aluminum garnet doped with cerium (YAG:Ce). In the end, heat treatment will be carried out at various temperatures and the effect of sintering temperature on the crystal phase and morphology will be studied. To highlight the phase transition from amorphous to crystalline state, a Rigaku SmartLab X-ray Diffraction System was used. Moreover, by the X-Ray diffraction pattern we evidenced the presence of the intermediate phases such as the main oxides, the metastable phases with perovskite (YAP) and monoclinic (YAM) structure and finally the garnet phase (YAG). The presence of the dopant in the crystalline structure was demonstrated. The microstructure and morphology evolution of the particles were assessed by using the FEI Nova NanoSEM system. Getting garnet phase and particles with spherical and smooth surfaces at the nanoscale range after a sintering treatment at 1100 °C indicates a phosphor applicable in optoelectronics.