Crystal-Field Analysis and Temperature-Dependent Luminescence Mechanism of Broadband Near-Infrared Na$_3$Al$_2$Li$_3$F$_{12}$:Cr$^{3+}$ Phosphors

Xinlei Zang; Yagang Feng; Yumeng Li; Ziyu Liu; Lei Duan; Shichang Cai; Hanlu Zhang; Chen Hu; Zhenzhen Zhou; Denis Yu. Kosyanov; Jiang Li

doi:10.62762/JAMR.2026.189146

Article Information

Published in Journal of Advanced Materials Research

Volume/Issue Volume 2, Issue 4, 2026

Pages 285-298

Abstract

Garnet-structured fluoride phosphors are attractive for phosphor-converted near-infrared light-emitting diodes (NIR pc-LEDs) owing to their broadband emission and thermal stability. Herein, pure-phase Na$_3$Al$_{2-x}$Cr$_x$Li$_3$F$_{12}$ (x = 0--0.16; NALF:Cr$^{3+}$) phosphors were synthesized hydrothermally, and their structure, morphology, crystal field, and luminescence were systematically investigated. Crystal-field analysis yielded a Dq/B of $\sim$2.18, confirming a weak crystal-field environment for Cr$^{3+}$. Under 430 nm excitation, all samples show a broad NIR band over 650--900 nm with a FWHM of $\sim$101 nm, ascribed to the $^4T_{2g}\rightarrow{}^4A_{2g}$ transition. Fluorescence decay and time-resolved emission spectroscopy indicate that Cr$^{3+}$ solely replaces octahedral Al$^{3+}$, forming a single luminescent center, optimal at x = 0.08. The phosphor retains over 67% of its room-temperature intensity at 423 K, and temperature-dependent photoluminescence reveals the zero-phonon line (ZPL) of the $^4T_{2g}\rightarrow{}^4A_{2g}$ transition at 80 K, offering deeper insight into the Cr$^{3+}$ luminescence mechanism in fluoride garnets. NALF:Cr$^{3+}$ is thus a promising broadband NIR phosphor for blue-LED-pumped pc-LEDs.

Graphical Abstract

$Crystal-Field Analysis and Temperature-Dependent Luminescence Mechanism of Broadband Near-Infrared Na$_3$Al$_2$Li$_3$F$_{12}$:Cr$^{3+}$ Phosphors$

Keywords

Cr$^{3+}$ fluoride phosphor Na$_3$Al$_2$Li$_3$F$_{12}$ near-infrared emission luminescence dynamics temperature-dependent photoluminescence

Data Availability Statement

Data will be made available on request.

Funding

This work was supported in part by the National Natural Science Foundation of China under Grant 52502135 and Grant 52402142, in part by the Natural Science Foundation of Henan Province of China under Grant 252300420429, in part by the International Cooperation and Exchange Project of the National Natural Science Foundation of China under Grant W2512070, and in part by the Shanghai Partnership Research Program under Grant 25HB2706600.

Conflicts of Interest

Denis Yu. Kosyanov served as an Editorial Board Member, and Jiang Li served as an Associate Editor of the Journal of Advanced Materials Research at the time of manuscript submission. To ensure the integrity of the peer-review process, neither Denis Yu. Kosyanov nor Jiang Li was involved in the editorial handling, peer review, or decision-making process for this manuscript, which was handled independently by another editor. The remaining authors declare no conflicts of interest.

AI Use Statement

The authors declare that no generative AI was used in the preparation of this manuscript.

Ethical Approval and Consent to Participate

Not applicable.

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APA Style

Zang, X., Feng, Y., Li, Y., Liu, Z., Duan, L., Cai, S., Zhang, H., Hu, C., Zhou, Z., Kosyanov, D. Y., & Li, J. (2026). Crystal-Field Analysis and Temperature-Dependent Luminescence Mechanism of Broadband Near-Infrared Na3Al2Li3F12:Cr3+ Phosphors. Journal of Advanced Materials Research, 2(3), 285-298. https://doi.org/10.62762/JAMR.2026.189146

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TY  - JOUR
AU  - Zang, Xinlei
AU  - Feng, Yagang
AU  - Li, Yumeng
AU  - Liu, Ziyu
AU  - Duan, Lei
AU  - Cai, Shichang
AU  - Zhang, Hanlu
AU  - Hu, Chen
AU  - Zhou, Zhenzhen
AU  - Kosyanov, Denis Yu.
AU  - Li, Jiang
PY  - 2026
DA  - 2026/09/20
TI  - Crystal-Field Analysis and Temperature-Dependent Luminescence Mechanism of Broadband Near-Infrared Na$_3$Al$_2$Li$_3$F$_{12}$:Cr$^{3+}$ Phosphors
JO  - Journal of Advanced Materials Research
T2  - Journal of Advanced Materials Research
JF  - Journal of Advanced Materials Research
VL  - 2
IS  - 4
SP  - 285
EP  - 298
DO  - 10.62762/JAMR.2026.189146
UR  - https://www.icck.org/article/abs/JAMR.2026.189146
KW  - Cr$^{3+}$
KW  - fluoride phosphor
KW  - Na$_3$Al$_2$Li$_3$F$_{12}$
KW  - near-infrared emission
KW  - luminescence dynamics
KW  - temperature-dependent photoluminescence
AB  - Garnet-structured fluoride phosphors are attractive for phosphor-converted near-infrared light-emitting diodes (NIR pc-LEDs) owing to their broadband emission and thermal stability. Herein, pure-phase Na$_3$Al$_{2-x}$Cr$_x$Li$_3$F$_{12}$ (x = 0--0.16; NALF:Cr$^{3+}$) phosphors were synthesized hydrothermally, and their structure, morphology, crystal field, and luminescence were systematically investigated. Crystal-field analysis yielded a Dq/B of $\sim$2.18, confirming a weak crystal-field environment for Cr$^{3+}$. Under 430 nm excitation, all samples show a broad NIR band over 650--900 nm with a FWHM of $\sim$101 nm, ascribed to the $^4T_{2g}\rightarrow{}^4A_{2g}$ transition. Fluorescence decay and time-resolved emission spectroscopy indicate that Cr$^{3+}$ solely replaces octahedral Al$^{3+}$, forming a single luminescent center, optimal at x = 0.08. The phosphor retains over 67% of its room-temperature intensity at 423 K, and temperature-dependent photoluminescence reveals the zero-phonon line (ZPL) of the $^4T_{2g}\rightarrow{}^4A_{2g}$ transition at 80 K, offering deeper insight into the Cr$^{3+}$ luminescence mechanism in fluoride garnets. NALF:Cr$^{3+}$ is thus a promising broadband NIR phosphor for blue-LED-pumped pc-LEDs.
SN  - 3070-5851
PB  - Institute of Central Computation and Knowledge
LA  - English
ER  -

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@article{Zang2026CrystalFie,
  author = {Xinlei Zang and Yagang Feng and Yumeng Li and Ziyu Liu and Lei Duan and Shichang Cai and Hanlu Zhang and Chen Hu and Zhenzhen Zhou and Denis Yu. Kosyanov and Jiang Li},
  title = {Crystal-Field Analysis and Temperature-Dependent Luminescence Mechanism of Broadband Near-Infrared Na\$\_3\$Al\$\_2\$Li\$\_3\$F\$\_{12}\$:Cr\$^{3+}\$ Phosphors},
  journal = {Journal of Advanced Materials Research},
  year = {2026},
  volume = {2},
  number = {4},
  pages = {285-298},
  doi = {10.62762/JAMR.2026.189146},
  url = {https://www.icck.org/article/abs/JAMR.2026.189146},
  abstract = {Garnet-structured fluoride phosphors are attractive for phosphor-converted near-infrared light-emitting diodes (NIR pc-LEDs) owing to their broadband emission and thermal stability. Herein, pure-phase Na\$\_3\$Al\$\_{2-x}\$Cr\$\_x\$Li\$\_3\$F\$\_{12}\$ (x = 0--0.16; NALF:Cr\$^{3+}\$) phosphors were synthesized hydrothermally, and their structure, morphology, crystal field, and luminescence were systematically investigated. Crystal-field analysis yielded a Dq/B of \$\sim\$2.18, confirming a weak crystal-field environment for Cr\$^{3+}\$. Under 430 nm excitation, all samples show a broad NIR band over 650--900 nm with a FWHM of \$\sim\$101 nm, ascribed to the \$^4T\_{2g}\rightarrow{}^4A\_{2g}\$ transition. Fluorescence decay and time-resolved emission spectroscopy indicate that Cr\$^{3+}\$ solely replaces octahedral Al\$^{3+}\$, forming a single luminescent center, optimal at x = 0.08. The phosphor retains over 67\% of its room-temperature intensity at 423 K, and temperature-dependent photoluminescence reveals the zero-phonon line (ZPL) of the \$^4T\_{2g}\rightarrow{}^4A\_{2g}\$ transition at 80 K, offering deeper insight into the Cr\$^{3+}\$ luminescence mechanism in fluoride garnets. NALF:Cr\$^{3+}\$ is thus a promising broadband NIR phosphor for blue-LED-pumped pc-LEDs.},
  keywords = {Cr\$^{3+}\$, fluoride phosphor, Na\$\_3\$Al\$\_2\$Li\$\_3\$F\$\_{12}\$, near-infrared emission, luminescence dynamics, temperature-dependent photoluminescence},
  issn = {3070-5851},
  publisher = {Institute of Central Computation and Knowledge}
}

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