Constructing double perovskite Eu3+/Mn4+ -codoped La2Mg1.33Ta0.67O6 phosphors for high sensitive dual-mode optical thermometers

Abstract

To overcome the challenges of optical thermometers with high sensitivities, a series of Mn4+-doped and Eu3+/Mn4+ co-doped La2Mg1.33Ta0.67O6 phosphors were designed, in which their phase structure, morphology, luminescence and thermometric properties were systematically studied. Excited at 355 nm, Mn4+-doped La2Mg1.33Ta0.67O6 phosphors emit intense red emissions and their intensities are impacted by Mn4+ content, where the concentration quenching mechanism is dominated by dipole-dipole interaction. Moreover, Eu3+/Mn4+-codoepd La2Mg1.33Ta0.67O6 phosphors can be excited by different wavelengths (i.e., 300 and 465 nm) and their luminescence behaviors are able to be manipulated by adjusting Eu3+ content. Through analyzing the diverse responses of Eu3+ and Mn4+ emissions to temperature via fluorescence intensity rate (FIR) technology, the thermometric performance of resultant phosphors was investigated and its maximum absolute and relative sensitivities are 0.057 and 2.72% K−1, respectively. Furthermore, based on the temperature-dependent lifetime of Mn4+, one knows that the maximum relative sensitivity of synthesized compounds is 3.42% K−1. Notably, the FIR and lifetime based sensitivities of prepared phosphors are independent on excitation wavelength. These results suggest that Eu3+/Mn4+-codoped La2Mg1.33Ta0.67O6 phosphors are promising luminescent platforms for dual-model optical thermometry. Ultimately, our findings also provide a facile strategy to develop high sensitive thermosensitive luminescent materials.