Enhanced luminescence properties of Ca1+xSr2−xAl2O6:Eu3+ (0 ≤ x ≤ 1) red phosphors based on composition modulation

Abstract

A series of solid solution Ca_1+xSr_2−xAl₂O₆:Eu³⁺ (0 ≤ x ≤ 1) phosphors has been successfully synthesized via a high-temperature solid-state method. The phase structures, photoluminescence performances, and fluorescence lifetimes, as well as the thermal stability properties, have been systematically investigated. All of the samples possess a cubic structure system and belong to the Pa(205) space-group. Owing to the ⁵D₀ → ⁷F₂ transition of the Eu³⁺ ions, the photoluminescence emission (PL) spectra demonstrate a strong red emission band at around 612 nm. As the Sr²⁺ ions have been substituted by Ca²⁺ ions in the CaSr₂Al₂O₆:Eu³⁺ composition, the luminous intensities are gradually enhanced owing to the average bond lengths of Ca–O, Sr/Ca–O, and Sr–O, which are shorter. In addition, the PL intensities at 423 K for the CaSr₂Al₂O₆:0.02Eu³⁺, Ca_1.5Sr_1.5Al₂O₆:0.02Eu³⁺, and Ca₂SrAl₂O₆:0.02Eu³⁺ phosphors retain 84.5%, 76.1%, and 75.7% of their intensities, respectively, compared with their initial intensities at 303 K. The results demonstrate that high-performance Eu³⁺-activated red-emitting phosphors can be obtained via cation substitution.