Microwave-hydrothermal synthesis, near ultraviolet/infrared-excited green fluorescence and ratiometric thermometry of Er3+-activated iodate phosphors

Abstract

Fluorescence intensity ratio (FIR) technique has been a promising non-contact thermometry method owing to the characteristics of rapid response and exceptional resolution. In this study, a new iodate phosphor NaYI4O12:Er3+ (NYIO:Er3+) is synthesized via a microwave-assisted hydrothermal method. It exhibits bright green emission under 380 and 980 nm excitations. The power-dependent upconversion and Er3+ content-dependent downshifting performances are investigated. Excited by 380 nm, the temperature-dependent FIR originating from thermally coupled levels of Er3+ are discussed in detail. The resulting material displays outstanding temperature sensing properties across the temperature range of 298–523 K. The absolute and relative sensitivities can reach the maximum values of 0.51 × 10−2 K−1 and 1.3 % K−1, separately. Meanwhile, the reliability and repeatability of the temperature sensing characteristics are verified. The result demonstrates that the Er3+-activated iodate phosphor NaYI4O12:Er3+ is a promising candidate in non-contact optical thermometry domain.