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

Author(s)

Andriotti Jr, Mauro Antonio ; Bernardi, Maria Ines Basso ; Mesquita, Alexandre

• Document type: Journal article
• Source: Journal of Alloys and Compounds; v. 955, p. 7-pg., 2023-04-26.

Abstract

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 pre-sented 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 dis-placement, 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 con-centration 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 asso-ciated with intermediary electronic levels in the band gap caused by these intrinsic defects.(c) 2023 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/12993-4 - Synthesis and characterization of luminescent nanostructured semiconductor materials
• Grantee: Alexandre Mesquita
• Support Opportunities: Regular Research Grants