Heteronuclear lanthanide titanium‐oxygen cluster luminescence thermometer with adjustable operating range and sensitivity
Tingting Li, Jin-Zhe Liu, Shaojiang Zheng, Feng Jiang, Jinyu Liu, Weinan Dong, Yù Zhang, Shao‐Ping Zheng, Ya‐Nan Li, Zhennan Wu, Xue Bai
Abstract
Abstract Given customizable crystal structure and intriguing optical properties, lanthanide titanium‐oxygen clusters (LTOCs) with atomic‐level accuracy have gained a lot of interest. In this study, we prepared [Ln 9 Ti 2 (μ 4 –O)(μ 3 –OH) 14 (acac) 17 (CH 3 O) 2 (CH 3 OH) 3 ] (Ln = Tb x Eu 9− x ( x = 0, 4, 6, 7, 8, 9), Hacac = acetylacetone), Tb 3+ and Eu 3+ co‐doped LTOCs, to modify the optical properties for the luminescence thermometer. In detail, the serial LTOCs display dual characteristic emission peaks of 5 D 4 → 7 F 5 for Tb 3+ and 5 D 0 → 7 F 2 for Eu 3+ at 548 and 616 nm, respectively, under 330 nm excitation. Effective energy transfer (ET) between Tb 3+ ions and Eu 3+ ions was revealed in terms of both emission spectra and luminescence lifetime. The 5 D 0 → 7 F 2 emission intensity of Eu 3+ ions at 616 nm is maximally enhanced (by a factor of 11.2) with a change in the relative molar ratio of Tb 3+ to Eu 3+ , along with a change in the ET efficiency of Tb 3+ → Eu 3+ . In addition, the luminescent color changes from red, orange, yellow, to green. This precise control of the ET process between rare‐earth ions allows {Tb 6 Eu 3 Ti 2 } to reach a maximum relative sensitivity of 1.241 K −1 at 355 K, which is an enhancement of up to 4.6‐fold with respect to the previously reported homonuclear emission, holding great potential in the optical thermometers.