Phase dependent luminescence properties of Pr3+ doped BaLu2F8–BaLuF5 materials
(2025) In Optical Materials 167.- Abstract
This work presents a comparative luminescence study of Pr3+ doped phase-pure BaLuF5 and mixed-phase BaLu2F8 – BaLuF5 materials synthesized via a hydrothermal route. The spectroscopic studies were mainly performed for phase-pure BaLuF5 and two mixed-phase materials, which, according to structural and phase compositional analysis, contained 90 or 70 wt% of orthorhombic BaLu2F8 and 10 or 30 wt% of cubic BaLuF5, respectively. Low-temperature time-integrated photoluminescence measurements under both host excitation at 45 eV and intracenter excitation of Pr3+ ions at 6.75 eV revealed pronounced differences in luminescence between the... (More)
This work presents a comparative luminescence study of Pr3+ doped phase-pure BaLuF5 and mixed-phase BaLu2F8 – BaLuF5 materials synthesized via a hydrothermal route. The spectroscopic studies were mainly performed for phase-pure BaLuF5 and two mixed-phase materials, which, according to structural and phase compositional analysis, contained 90 or 70 wt% of orthorhombic BaLu2F8 and 10 or 30 wt% of cubic BaLuF5, respectively. Low-temperature time-integrated photoluminescence measurements under both host excitation at 45 eV and intracenter excitation of Pr3+ ions at 6.75 eV revealed pronounced differences in luminescence between the two systems. The phase-pure BaLuF5 material exhibited only narrow 4f2→4f2 transitions of Pr3+, because the 4f15d1states are energetically situated above the highest lying 4f2 1S0 level. In contrast, the BaLu2F8 rich mixed-phase material showed multiple intense broad bands in the UV-C spectral region due to the 4f15d1→4f2 transitions, in addition to intense 4f2→4f2 emissions in the visible spectral range, indicating enhanced energy transfer processes influenced by the orthorhombic host matrix. A cascade emission mechanism in Pr3+ starting from the 1S0 level was revealed in both materials by the presence of characteristic emissions at 3.04 eV (1S0→1I6) and 2.57 eV (3P0→3H4) appearing in two sequent radiative relaxation stages. Time-integrated excitation spectra highlighted distinct excitation bands associated with different Pr3+ energy levels populated below the fundamental absorption edge. Time-resolved spectroscopy of the 4f15d1→4f2 emissions revealed bi-exponential decay kinetics, distinguishing surface-perturbed and bulk Pr3+ centers, with significantly different lifetimes in each phase. The varying intensity ratio of the 4f15d1→4f2 and 4f2→4f2 emissions demonstrates that, depending on the phase composition, it is possible to control the nature of Pr3+ emissions, enabling the design of multifunctional luminescent nanomaterials for diverse applications of deep UV emissions in phototherapy and optoelectronics.
(Less)
- author
- Maji, Sanu Bifal ; Vanetsev, Alexander ; Mändar, Hugo ; Nagirnyi, Vitali ; Chernenko, Kirill LU ; Kozlova, Jekaterina ; Kotlov, Aleksei ; Smortsova, Yevheniia and Kirm, Marco
- organization
- publishing date
- 2025-10
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Mixed-phase fluorides, Nanoparticle, Pr 4f5d→4f transitions, Pr 4f S→4f transitions, Time-resolved luminescence spectra, UV-C radiation
- in
- Optical Materials
- volume
- 167
- article number
- 117315
- publisher
- Elsevier
- external identifiers
-
- scopus:105010677004
- ISSN
- 0925-3467
- DOI
- 10.1016/j.optmat.2025.117315
- language
- English
- LU publication?
- yes
- id
- a6d615c1-cdb2-40f6-98eb-d472953de479
- date added to LUP
- 2025-10-31 10:24:35
- date last changed
- 2025-10-31 10:25:46
@article{a6d615c1-cdb2-40f6-98eb-d472953de479,
abstract = {{<p>This work presents a comparative luminescence study of Pr<sup>3+</sup> doped phase-pure BaLuF<sub>5</sub> and mixed-phase BaLu<sub>2</sub>F<sub>8</sub> – BaLuF<sub>5</sub> materials synthesized via a hydrothermal route. The spectroscopic studies were mainly performed for phase-pure BaLuF<sub>5</sub> and two mixed-phase materials, which, according to structural and phase compositional analysis, contained 90 or 70 wt% of orthorhombic BaLu<sub>2</sub>F<sub>8</sub> and 10 or 30 wt% of cubic BaLuF<sub>5</sub>, respectively. Low-temperature time-integrated photoluminescence measurements under both host excitation at 45 eV and intracenter excitation of Pr<sup>3+</sup> ions at 6.75 eV revealed pronounced differences in luminescence between the two systems. The phase-pure BaLuF<sub>5</sub> material exhibited only narrow 4f<sup>2</sup>→4f<sup>2</sup> transitions of Pr<sup>3+</sup>, because the 4f<sup>1</sup>5d<sup>1</sup>states are energetically situated above the highest lying 4f<sup>2</sup> <sup>1</sup>S<sub>0</sub> level. In contrast, the BaLu<sub>2</sub>F<sub>8</sub> rich mixed-phase material showed multiple intense broad bands in the UV-C spectral region due to the 4f<sup>1</sup>5d<sup>1</sup>→4f<sup>2</sup> transitions, in addition to intense 4f<sup>2</sup>→4f<sup>2</sup> emissions in the visible spectral range, indicating enhanced energy transfer processes influenced by the orthorhombic host matrix. A cascade emission mechanism in Pr<sup>3+</sup> starting from the <sup>1</sup>S<sub>0</sub> level was revealed in both materials by the presence of characteristic emissions at 3.04 eV (<sup>1</sup>S<sub>0</sub>→<sup>1</sup>I<sub>6</sub>) and 2.57 eV (<sup>3</sup>P<sub>0</sub>→<sup>3</sup>H<sub>4</sub>) appearing in two sequent radiative relaxation stages. Time-integrated excitation spectra highlighted distinct excitation bands associated with different Pr<sup>3+</sup> energy levels populated below the fundamental absorption edge. Time-resolved spectroscopy of the 4f<sup>1</sup>5d<sup>1</sup>→4f<sup>2</sup> emissions revealed bi-exponential decay kinetics, distinguishing surface-perturbed and bulk Pr<sup>3+</sup> centers, with significantly different lifetimes in each phase. The varying intensity ratio of the 4f<sup>1</sup>5d<sup>1</sup>→4f<sup>2</sup> and 4f<sup>2</sup>→4f<sup>2</sup> emissions demonstrates that, depending on the phase composition, it is possible to control the nature of Pr<sup>3+</sup> emissions, enabling the design of multifunctional luminescent nanomaterials for diverse applications of deep UV emissions in phototherapy and optoelectronics.</p>}},
author = {{Maji, Sanu Bifal and Vanetsev, Alexander and Mändar, Hugo and Nagirnyi, Vitali and Chernenko, Kirill and Kozlova, Jekaterina and Kotlov, Aleksei and Smortsova, Yevheniia and Kirm, Marco}},
issn = {{0925-3467}},
keywords = {{Mixed-phase fluorides; Nanoparticle; Pr 4f5d→4f transitions; Pr 4f S→4f transitions; Time-resolved luminescence spectra; UV-C radiation}},
language = {{eng}},
publisher = {{Elsevier}},
series = {{Optical Materials}},
title = {{Phase dependent luminescence properties of Pr<sup>3+</sup> doped BaLu<sub>2</sub>F<sub>8</sub>–BaLuF<sub>5</sub> materials}},
url = {{http://dx.doi.org/10.1016/j.optmat.2025.117315}},
doi = {{10.1016/j.optmat.2025.117315}},
volume = {{167}},
year = {{2025}},
}