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

• Published in: Journal of alloys and compounds 2023-09, Vol.955, p.170147, Article 170147
• Main Authors: Júnior, Mauro Antonio Andriotti, Bernardi, Maria Inês Basso, Mesquita, Alexandre
• Format: Article
• Language: English
• Subjects: Hydrothermal; Local structure; Photoluminescence; SrTiO3:Pr; XANES and EXAFS
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.170147

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. •Sr0.998Pr0.002Ti1−yAlyO3 phosphor mesocrystals were prepared via hydrothermal route.•The morphology presents microcube shape of the mesocrystals without spurious phases.•X-ray absorption spectroscopy detected local disorder and O vacancies.•Lower symmetry around Pr3+ increases the probabilities of the 4f transitions.•Intrinsic defects generate a broad emission in photoluminescence spectra.