This study reports the synthesis and multifunctional characterization of Tm3⁺-doped SrLaAlO4 (SrLa1–xTmxAlO4) blue-emitting phosphors (1.0–7.0 mol. %) prepared via urea-based combustion method. X-ray diffraction analysis confirmed a pure tetragonal phase for all the samples made with Tm3+. The characterization by microscopy revealed a particle size reduction from 1.03 to 0.386 µm with increasing Tm3⁺ concentration, indicating suppressed grain growth due to dopant-induced lattice strain. Under 355 and 254 nm excitation, intense blue emission at 462 nm was observed, assigned to the 1G4 → 3H6 transition of Tm3⁺. The highest luminescence intensity was observed for the sample made with 5.0 mol. % of Tm3⁺, beyond this concentration, quenching effects occurred and the luminescence decreased. Thermoluminescence (TL) response was evaluated under β-irradiation (10 °C/s) using UV excitation at 385, 365, and 265 nm. Using the Chen method, kinetic parameters—including activation energy (E), frequency factor (s), and order of kinetics (b)—were determined, revealing stable trap centers suitable for dosimetry applications. Notably, the most intense TL was observed for the sample made with 2.0 mol. % of Tm3. In photocatalytic tests under solar irradiation, the sample made with 1.0 mol. % of Tm3⁺ produced 83% of degradation for methylene blue dye, probably due to minimized recombination centers and enhanced charge separation. In general, it was demonstrated that the SrLa1–xTmxAlO4 system has a triple functionality and the optimum concentration were 5 mol. % for PL, 2 mol. % for TL, and 1 mol. % for photocatalytic activity. Moreover, the TL emission at 265 nm was correlated for the first time with refractive index and bandgap changes. The results above indicate that SrLa1–xTmxAlO4 is a promising candidate for UV-C dosimetry. Simultaneously, the degradation percentage for MB (produced by SrLa1–x TmxAlO4 phosphors) surpasses these previously reported for Sr-aluminate-based photocatalysts. Hence, the SrLa1–x TmxAlO4 material has potential for environmental remediation, dosimetry and lighting applications.

Photo/thermo-luminescent properties of Tm-doped SrLaAlO₄ phosphors and their use for the degradation of methylene blue dye

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发表日期：

2026年6月15日

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Nelson Oshogwue Etafo,
Carlos Eduardo Rodriguez-Garcia,
Jorge Oliva,
Claudia Magdalena Lopez-Badillo

摘要

This study reports the synthesis and multifunctional characterization of Tm³⁺-doped SrLaAlO₄ (SrLa_1–xTm_xAlO₄) blue-emitting phosphors (1.0–7.0 mol. %) prepared via urea-based combustion method. X-ray diffraction analysis confirmed a pure tetragonal phase for all the samples made with Tm³⁺. The characterization by microscopy revealed a particle size reduction from 1.03 to 0.386 µm with increasing Tm³⁺ concentration, indicating suppressed grain growth due to dopant-induced lattice strain. Under 355 and 254 nm excitation, intense blue emission at 462 nm was observed, assigned to the ¹G₄ → ³H₆ transition of Tm³⁺. The highest luminescence intensity was observed for the sample made with 5.0 mol. % of Tm³⁺, beyond this concentration, quenching effects occurred and the luminescence decreased. Thermoluminescence (TL) response was evaluated under β-irradiation (10 °C/s) using UV excitation at 385, 365, and 265 nm. Using the Chen method, kinetic parameters—including activation energy (E), frequency factor (s), and order of kinetics (b)—were determined, revealing stable trap centers suitable for dosimetry applications. Notably, the most intense TL was observed for the sample made with 2.0 mol. % of Tm³. In photocatalytic tests under solar irradiation, the sample made with 1.0 mol. % of Tm³⁺ produced 83% of degradation for methylene blue dye, probably due to minimized recombination centers and enhanced charge separation. In general, it was demonstrated that the SrLa_1–xTm_xAlO₄ system has a triple functionality and the optimum concentration were 5 mol. % for PL, 2 mol. % for TL, and 1 mol. % for photocatalytic activity. Moreover, the TL emission at 265 nm was correlated for the first time with refractive index and bandgap changes. The results above indicate that SrLa_1–xTm_xAlO₄ is a promising candidate for UV-C dosimetry. Simultaneously, the degradation percentage for MB (produced by SrLa_1–x Tm_xAlO₄ phosphors) surpasses these previously reported for Sr-aluminate-based photocatalysts. Hence, the SrLa_1–x Tm_xAlO₄ material has potential for environmental remediation, dosimetry and lighting applications.

Photo/thermo-luminescent properties of Tm-doped SrLaAlO4 phosphors and their use for the degradation of methylene blue dye

摘要

Photo/thermo-luminescent properties of Tm-doped SrLaAlO₄ phosphors and their use for the degradation of methylene blue dye