Self-calibrated ratiometric thermometers and multi-mode anti-counterfeiting based on Ca2LaNbO6:Pr3+ optical material

Optical materials have been extensively used in thermometers and anti-countering for their non-contact, advantageous rapid, and high precision properties. Herein, a double-perovskite Ca2LaNbO6:Pr3+ color-tunable phosphor was synthesized. The emissions (blue, green, red1, and red2) from Ca2LaNbO6:Pr3+ phosphor have different temperature-dependent properties because of the thermal quenching channel generated by the intervalence charge transfer state between Pr3+ and Nb5+ ions. They can be used to realize four fluorescence intensity ratio models (Green/Blue, Green/Red2, Red1/Blue and Red1/Red2) to measure temperature with high absolute and relative sensitivities. Moreover, using the Ca2LaNbO6:Pr3+ phosphor and the carbon dots with green afterglow to create anti-counterfeiting patterns, the multi-mode anti-counterfeiting under different portable lamps (254 nm and 365 nm) was realized. Therefore, the prepared multifunctional phosphor indicated a potential application in both optical temperature sensing and anti-counterfeiting simultaneously.