Multiple optical thermometry and dynamic anti‐counterfeiting based on multicolor emission in Y ₂ GaSbO ₇ :Bi ³⁺ ,Er ³⁺ phosphor

Abstract Optical thermometric and anti‐counterfeiting multifunctional materials hold great promise for practical applications, yet their development continues to encounter considerable challenges. Here, we successfully developed a new Bi 3+ ,Er 3+ co‐doped Y 2 GaSbO 7 powder with multicolor luminescence. Through adjusting the excitation wavelengths, emissions in violet, blue, green, and orange are achieved. The phosphor demonstrates remarkable thermochromism due to the distinct temperature‐dependent luminescence of Bi 3+ and Er 3+ , confirmed under irradiation at 312 or 980 nm. By reducing the power of 980 nm laser or increasing the laser‐to‐sample distance, the emitting color can be precisely tuned from gold‒yellow or yellow‒green to orange‒red. These diverse luminescent characteristics enable the creation of a multilevel anti‐counterfeiting system. Moreover, a four‐mode optical thermometry with an optimal relative sensitivity of 1.98% K −1 , a high thermal resolution of 0.15 K, and signal reversibility was established using fluorescence intensity ratio and fluorescence decay time. These results disclose that Y 2 GaSbO 7 :Bi 3+ ,Er 3+ phosphor is a promising candidate for temperature monitoring and dynamic anti‐counterfeiting applications.