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

The Sr4Al14O25:Eu2+/3+ phosphor was synthesized in air via conventional high-temperature solid-state reaction. Eu3+ in the host lattice was partially self-reduced to Eu2+, and the characteristic excitation and emission of Eu2+ and Eu3+ were detected simultaneously. Due to the different temperature quenching mechanisms of Eu2+ and Eu3+, the luminescent performance and fluorescence intensity ratio of Eu2+/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 Sr4Al14O25:Eu2+/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 Eu2+ and Eu3+ provide strong signal discrimination for temperature measurement. All the results indicate that the Sr4Al14O25:Eu2+/3+ phosphor possesses excellent temperature-sensing characteristic and can be a promising candidate for ratiometric optical thermometry applications.