Dual‑functional application of Ca_(2)Ta_(2)O_(7):Bi^(3+)/Eu^(3+)phosphors in multicolor tunable optical thermometry and WLED

A series of Bi^(3+)/Eu^(3+)co-doped Ca_(2)Ta_(2)O_(7)(CTO:Bi^(3+)/Eu^(3+))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^(3+)/Eu^(3+)and utilizing the energy transfer from Bi^(3+)to Eu^(3+),the tunable color emission ranging from green to reddish-orange was realized.The designed CTO:0.04Bi^(3+)/Eu^(3+)optical thermometers exhibit signifcant thermochromism,superior stability,and repeatability,with maximum sensitivities of Sa=0.055 K^(−1)(at 510 K)and Sr=1.298%K^(−1)(at 480 K)within the temperature range of 300−510 K,owing to the diferent thermal quenching behaviors between Bi^(3+)and Eu^(3+)ions.These features indicate the potential application prospects of the prepared samples in visualized thermometer or hightemperature safety marking.Furthermore,leveraging the excellent zero-thermal-quenching performance,outstanding acid/alkali resistance,and color stability of CTO:0.04Bi^(3+)/0.16Eu^(3+)phosphor,a WLED device with a high Ra 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^(3+)/0.16Eu^(3+)in near-UV pumped WLED devices.