High-sensitive temperature sensing based on thermal-enhanced emission and non-thermally coupled energy levels of white upconversion luminescence system

Na3Y(VO4)(2):Nd3+,Yb3+,Ho3+,Tm3+ phosphors present significantly improved sensitivity of optical temperature sensing based on thermal-enhanced upconversion luminescence and non-thermally coupled energy levels. Under 808 nm excitation, white upconversion luminescence is successfully achieved in Nd3+-sensitized system. In addition, the emissions intensities originated from (4)G(5/2)-> I-4(9/2) transition of Nd3+ and F-3(2,3)-> H-3(6) transition of Tm3+ gradually increase with elevating temperature owning to the thermal population effects, as opposed to the blue ((1)G(4)-> H-3(6) transition of Tm3+), green ((S2,F4)-S-5-F-5 -> I-5(8) transition of Ho3+) and red (F-5(5)-> I-5(8) transition of Ho3+) emissions intensities show continuous decreasing trend. The temperature sensing behaviors are investigated by employing multiple non-thermally coupled energy levels. Based on non-thermally coupled energy levels of (4)G(5/2) (Nd3+)/(1)G(4) (Tm3+), the absolute and relative sensitivities are obtained to be 0.433 K-1 and 2.81 % K-1. These results demonstrate that the Na3Y(VO4)(2):Nd3+,Yb3+,Ho3+,Tm3+ phosphors with superior optical thermometry performance and white luminescence within a relatively wide temperature range can achieve optical applications in many fields.