SrTiO3:Pr,Al phosphor mesocrystals: The role of Al-doping in short-range and electronic structure and its influence on photoluminescence properties

• Autor(a) principal: Júnior, Mauro Antonio Andriotti [UNESP]
• Data de Publicação: 2023
• Outros Autores: Bernardi, Maria Inês Basso, Mesquita, Alexandre [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.jallcom.2023.170147; http://hdl.handle.net/11449/247233
• topic: Hydrothermal; Local structure; Photoluminescence; SrTiO3:Pr; XANES and EXAFS

Phosphor materials with narrow emission bands and high quantum efficiency have received a good amount of attention, suggesting the possibility of several applications in the field of optoelectronic devices. SrTiO3:Pr is an example of a material with these characteristics. In this study, mesocrystal samples of Sr0.998Pr0.002Ti1−yAlyO3 (SrTiO3:Pr,Al) were prepared via a hydrothermal route, and the morphology presented a microcube shape and pristine structure with Pm3m space group without any spurious phases for all Al concentrations. Measurements of X-ray absorption spectroscopy (XAS) at Ti K-, LII,III-, and O K-edges, calculated projected density of states, and Raman spectroscopy revealed that the hydrothermal method and Al incorporation cause a local symmetry breaking, deviating from the cubic structure, Ti off-center displacement, tilting of TiO6 octahedra, and O vacancies. As the Al content increases, the intensity of some emissions in the photoluminescence spectra also increases up to 3 at%. The disorder produced by Al concentration leads to a lower symmetry around Pr3+ sites, resulting in an increase in the probabilities of transitions for Pr3+ ions due to the mixing of the opposite parity in 4 f configurational levels. On the other hand, higher Al concentrations cause a decrease in the intensity of Pr emissions, which is related to their quenching because of O vacancies. Additionally, intrinsic defects due to the hydrothermal route and Al incorporation generate a broad emission in the photoluminescence spectra. This broad emission is associated with intermediary electronic levels in the band gap caused by these intrinsic defects.