A colorimetric optical thermometry of host-sensitized Pr-doped niobate phosphors based on electronic-rich-site strategy.

Most praseodymium-doped red-emitting phosphors need high-temperature synthesis conditions with a reducing atmosphere. The niobate matrix selected in this work provides a sufficient electron-rich-site environment for praseodymium through charge migration, and praseodymium can be self-reduced in air atmosphere, which is safe and environmentally friendly. By building the [NbO] group → Pr energy transfer and finely modifying the doping concentration of Pr ions, we constructed a dual-luminescence-system of the [NbO] group and Pr. Thereby, optical temperature measurement based on fluorescence intensity ratio (FIR) technology of Pr ions and [NbO] groups was carried out using non-thermal coupling pairs, through the Boltzmann fitting and integral calculation, the maximum S and S values were 2.25% K and 0.0049 K at 403 K and 443 K, respectively, the S value is four times that obtained from the thermal coupling of Pr ions, which exceeded most values previously reported for the fluorescence powder. Accordingly, we also studied the thermal sensitivity of Er ions and Eu ions mono-doped CaNbO substrates. Results reveal that CaNbO:Pr/Er/Eu phosphors have splendid temperature sensitivity and have far-reaching application prospects in the field of temperature measurements.