Excellent temperature sensing characteristics of europium ions self-reduction Sr3P4O13 phosphors for ratiometric luminescence thermometer

Eu2+/Eu3+ co-doped Sr3P4O13 phosphors were prepared by high temperature solid stated method in air atmosphere and studied in detail their luminescent properties in order to investigate the possible applications in temperature sensors. The broadband emission of Eu2+ ions and the linear emission band of Eu3+ ions can be observed in the photoluminescence (PL) spectra of Sr3P4O13: Eu2+/Eu3+ phosphors due to the self-reduction effect. X-ray photoelectron spectroscopy (XPS), PL spectra, and time-resolved fluorescence lifetime confirm the formation of double emission centers of Eu2+ and Eu3+ ions in Sr3P4O13 because of the self-reduction by charge compensation. In the Eu2+/Eu3+ co-activated Sr3P4O13 thermometric phosphor, the blue emission of Eu2+ ions and red emission of Eu3+ ions, can be used as fluorescence intensity ratio (FIR) signals. In addition, the mechanism is discussed in detail based on the experimental data, and the strong temperature dependence is explained from the point of view of thermal quenching. Additionally, benefited from their diverse thermal quenching behavior, the FIR of Eu3+ to Eu2+ is fitted very well, and Sa reached a maximum 0.008 K-1 at 573 K, while Sr reached a maximum of 1.06% K-1 at 353K. As a consequence, this work indicates that Sr3P4O13: Eu2+/Eu3+ phosphors could be widely applied in optical temperature sensors. (C) 2019 Elsevier B.V. All rights reserved.