Clarifying concentration quenching mechanisms by lattice site-occupation and luminescence kinetics of Eu3+-activated Cs2Mg2Mo3O12

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 11; no. 39; pp. 13548 - 13560
• Main Authors: Wei, Donglei, Yang, Xifeng, Liu, Yushen, Kim, Joo Hyun, Park, Sung Heum, Hyo Jin Seo, Bo Ram Lee
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 12.10.2023
• Subjects: Chromaticity; Doping; Energy transfer; Europium; Excitation; Lattices; Luminescence; Phosphors; Quenching; Spectral emittance; Spectrum analysis; Substitution reactions
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d3tc02484a

The Eu3+ ion is not only an efficient red-emitting activator, but also a well-known spectral probe. In this work, a series of Cs2Mg2Mo3O12:2xEu3+ (x = 0–0.1) phosphors are successfully synthesized using the solid-state reaction. Rietveld refinements confirmed the cubic structure of Eu3+-doped Cs2Mg2Mo3O12 with the P213 space group (no: 198), in which the activators substituted for the Cs+ lattice positions. The phosphor exhibited a sharp luminescence line at 613 nm (5D0 to 7F2 of Eu3+) with a half-bandwidth of approximately 1 nm. The remarkable CIE chromaticity coordinates (x = 0.66, y = 0.33) are close to the ideal red chromaticity specified by the NTSC. Unfortunately, the optimal luminescence of Cs2Mg2Mo3O12:2xEu3+ was quenched at a low concentration of 5.0 at% (x = 0.05). The quenching mechanism was analyzed through the Eu3+-site occupations and the corresponding dynamic spectra were obtained using the laser site-selective spectroscopy technique. In the samples with low doping levels of Cs2Mg2Mo3O12:2xEu3+ (x ≦ 0.05), only one Eu3+ center was regularly arranged on Cs(2) sites. Beyond this level of doping in Cs2Mg2Mo3O12:2xEu3+ (x = 0.07, 0.1), Eu3+ began to occupy Cs(1) sites in the lattices in addition to Cs(2). The site-selective luminescence and decay characteristics confirmed that the two Eu3+ centers occupying Cs(1) and Cs(2) sites had sufficient energy transfer (ET) between them. In this case, the excitation energy was easily lost during the excitation process. This study demonstrates that the substitution position of the Eu3+ activator in the lattice can greatly affect the quenching performance of red emission.