Reversible luminescence modulation and temperature‐sensing properties of Pr3+/Yb3+ codoped K0.5Na0.5NbO3 ceramics.

In this work, we have prepared a novel (K0.5Na0.5)0.99‐xPrxYb0.01NbO3 (abbreviated as KNN:xPr3+/0.01Yb3+, x = 0.0006, 0.0008, 0.001, 0.002, 0.003, and 0.004) ceramics, which possess visible UC emissions, photochromic (PC) and optical thermometric properties. Under the excitation of a 980‐nm diode laser, all the samples show the featured emissions of Pr3+ ions and the UC emission intensity is greatly dependent on the Pr3+ doping content. The optimal UC luminescence intensity is obtained at x = 0.001. All the prepared samples show a strong PC reaction, and a large luminescence quenching degree (ΔRt) of 74.94% is found. The optical thermometric properties of both the irradiated and unirradiated KNN:0.001Pr3+/0.01Yb3+ ceramics in the temperature range of 123‐573 K have been investigated via measuring the temperature‐dependent UC emission spectra of green emissions, which originate from the two 3P1 and 3P0 thermally coupled levels. It has been found that the prepared samples have both excellent PC behaviors and temperature‐sensing performances. These results suggest that the KNN:xPr3+/0.01Yb3+ ceramics are promising candidates for the applications in PC reaction and thermometers. [ABSTRACT FROM AUTHOR]