Dual-emitting phosphor Sr4Al14O25:Eu2+/3+ prepared in air for ratiometric temperature sensing

The Sr 4 Al 14 O 25 :Eu 2+/3+ phosphor was synthesized in air via conventional high-temperature solid-state reaction. Eu 3+ in the host lattice was partially self-reduced to Eu 2+ , and the characteristic excitation and emission of Eu 2+ and Eu 3+ were detected simultaneously. Due to the different temperature quenching mechanisms of Eu 2+ and Eu 3+ , the luminescent performance and fluorescence intensity ratio of Eu 2+/3+ co-activated phosphor presented great temperature dependence. With the increase of the operating temperature, the emitting color of the phosphor can be tuned from bluish green to white. The maximum absolute and relative temperature sensitivity of Sr 4 Al 14 O 25 :Eu 2+/3+ phosphor can be as high as 0.015 K −1 at 525 K and 1.1% K −1 at 375 K, respectively. In addition, the decoupled emission peaks of Eu 2+ and Eu 3+ provide strong signal discrimination for temperature measurement. All the results indicate that the Sr 4 Al 14 O 25 :Eu 2+/3+ phosphor possesses excellent temperature-sensing characteristic and can be a promising candidate for ratiometric optical thermometry applications.