Dual-mode Optical Thermometer Based on Fluorescence Intensity Ratio of Eu3+/Mn4+ Co-Doping Zinc Titanate Phosphors.

Zinc titanate phosphors containing Eu3+/ Mn4+ as active ions were synthesized by using the solid-state method. XRD patterns of the powders confirmed that the samples were a mixture of cubic Zn2TiO4 and hexagonal ZnTiO3 phases. The luminous intensity of ZTO: Eu3+phosphors and ZTO: Mn4+ phosphors both increased with the increase of doping concentration, reaching the maximum at 2 mol% Eu3+ and 0.3 mol% Mn4+, respectively. In the photoluminescence spectra of ZTO: Eu3+(2 mol%) phosphors with different Mn4+ doping amounts excited at 465 nm, the emission spectra revealed the characteristic peaks of Eu3+ with low Mn4+ content, and with the Mn4+ content increasing, the emission spectra contained both Mn4+ and Eu3+ luminescence peaks. In the variable temperature spectra, the relative sensitivity of the samples was improved with the concentration of Mn4+ increasing and achieved the maximum value of 3.2 %/K.