Findings of the research team of Peng Wu, a research fellow in the Analytical and Testing Center, Sichuan University, indicate thatα-AlF₃ (constituted by vertex sharing AlF₆octahedral unit) exhibited long-lived color-tunable phosphorescence emission, which could last up to 7 seconds and be observed by naked eyes.

The research findings were published under the title "Multicolor Ultralong Phosphorescence from Perovskite-Like Octahedral α-AlF3" in Nature Communications. Sichuan University is the first work unit. Peisheng Cao, a Class 2022 doctoral student of the College of Chemistry, was the first author, and Peng Wu is the corresponding author. “To exclude the potential influence from trace impurities, direct synthesis of AlF₃ through exposing aluminum metal of the highest purity available to HF vapor was carried out. As expected, similar emission properties were also obtained ---, confirming that the luminescence was exactly from AlF₃”(Introduction)

Luminescence properties of α-AlF₃ (calcinated from AlF₃·3H₂O).

Summary on the BX₆ octahedra-based luminescence.

“---here we propose that the BX₆ octahedron may be a core structure for luminescent inorganic materials. In this regard, excitation-dependent color-tunable phosphorescence is discovered from α-AlF₃ featuring AlF₆ octahedron. Through further exploration of the BX₆ unit by altering the dimension and changing the center metal (B) and ligand (X), luminescence from KAlF₄, (NH₄)₃AlF₆, AlCl₃, Al(OH)₃, Ga₂O₃, InCl₃, and CdCl₂ are also discovered. The phosphorescence of α-AlF₃ can be ascribed to clusterization-triggered emission, i.e., weak through space interaction of the n electrons of F atoms bring close proximity in the AlF₆ octahedra (inter/intra). These discoveries will deepen the understanding and contribute to further development of BX₆ octahedron-based luminescent materials.” (Abstract)

The authors gratefully acknowledgethe financial support from the National Natural Science Foundation of China (No. 21522505) and Sichuan Science and Technology Program (No. 2021YFH0124), and so forth.

https://www.nature.com/articles/s41467-022-33540-1。