Dual-functional application of CaTaO:Bi/Eu phosphors in multicolor tunable optical thermometry and WLED.

A series of Bi/Eu co-doped CaTaO (CTO:Bi/Eu) phosphors were prepared by high-temperature solid-state method for dual-emission center optical thermometers and white light-emitting diode (WLED) device. By modulating the doping ratio of Bi/Eu and utilizing the energy transfer from Bi to Eu, the tunable color emission ranging from green to reddish-orange was realized. The designed CTO:0.04Bi/Eu optical thermometers exhibit significant thermochromism, superior stability, and repeatability, with maximum sensitivities of S = 0.055 K (at 510 K) and S = 1.298% K (at 480 K) within the temperature range of 300-510 K, owing to the different thermal quenching behaviors between Bi and Eu ions. These features indicate the potential application prospects of the prepared samples in visualized thermometer or high-temperature safety marking. Furthermore, leveraging the excellent zero-thermal-quenching performance, outstanding acid/alkali resistance, and color stability of CTO:0.04Bi/0.16Eu phosphor, a WLED device with a high R value of 95.3 has been realized through its combination with commercially available blue and green phosphors, thereby demonstrating the potential application of CTO:0.04Bi/0.16Eu in near-UV pumped WLED devices.