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Three kinds of important red phosphors, the monoclinic Ln2O2SO4 (Ln=Gd, Eu), cubic Ln2O3 and hexagonal Ln2O2S were obtained through controlled calcination of single hydroxyl sulfate Ln2(OH)4SO4·nH2O (LLnHs) precursor. The conditions of the hydrothermal synthesis of LGdHs were investigated, and it was found that LGdHs can be obtained in pH range of 7-9. The micro-morphology changes from aggregated spheres to micro plates with increasing pH. Gd2(OH)4SO4·nH2O was transformed into Gd2O2SO4 via removal of hydration water (up to 340 oC) and dehydroxylation (340-800 oC), and finally change into Gd2O3 via desulfuration (800-1230 oC) in the air. Gd2O2S was obtained from Gd2(OH)4SO4·nH2O by calcination in reducing atmosphere (800-1200 oC). Photoluminescence excitation (PLE) studies showed broad and strong O-Eu CT bands at 260, 275, and 267 nm in Ln2O3, Ln2O2SO4 and Ln2O2S, respectively, and extra S-Eu CT band locates at 334 nm was observed in Ln2O2S. The strongest red emission corresponding to the electric dipole 5D0→7F2 transitions of the Eu3+ ions were observed at 613, 618, and 626 nm in Ln2O3, Ln2O2SO4 and Ln2O2S system, respectively. The quenching concentration of Ln2O2S (3%) is smaller than those of Ln2O2SO4 (6%) and Ln2O3 (6%), which is due to the fact that the average Eu3+-Eu3+ distance is smaller in Ln2O2S. The quenching mechanism was investigated, and it was found that the observed luminescence quenching was dominated by exchange interactions among Eu3+
ions.

権利情報:

• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

キーワード: Photoluminescence, Oxysulfate, Oxysulfide, Oxide, Hydroxyl sulfate

刊行年月日: 2023-11-08

出版者: Elsevier BV

掲載誌:

• ADVANCED POWDER TECHNOLOGY (ISSN: 09218831) vol. 34 issue. 12 p. 104271-104271

研究助成金:

原稿種別: 著者最終稿 (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4347

公開URL: https://doi.org/10.1016/j.apt.2023.104271

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更新時刻: 2025-11-08 08:30:33 +0900

MDRでの公開時刻: 2025-11-08 08:21:20 +0900