Optical temperature sensing characteristics of Gd2Ti2O7: Sm3+, Tm3+ phosphors

Abstract

In this experiment, Gd2Ti2O7: x% Sm3+, 1% Tm3+ (x = 0.1, 0.3, 0.5, 1) optical temperature sensing materials were created with the hydrothermal method, with urea used as the precipitant. The X-ray diffraction (XRD) analysis results showed that the samples we prepared had a face-centered cubic phase pyrochlore structure. As the field emission scanning electron microscope (FE-SEM) images illustrated, the morphology of the samples was irregularly spherical. Furthermore, by measuring the temperature-dependent emission spectrum of each sample, it was discovered that the Tm3+ had a significant thermal quenching phenomenon, while the Sm3+ had a slower thermal quenching trend, so their fluorescence intensity ratios (FIRs) varied significantly with the temperature. This variation could be used to represent the temperature. By comparing different samples, we found that the Sm3+ concentration rose and the absolute sensitivity of the samples rose gradually, while the relative sensitivity gradually became smaller and smaller. The maximal absolute sensitivity was 0.0686 K−1 (483 K, 1% Sm3+, 1% Tm3+), and the maximal relative sensitivity was 3.1% K−1 (297.7 K, 0.1% Sm3+, 1% Tm3+). At the same time, through observation, it was determined that the luminescence color of the Gd2Ti2O7: 0.1% Sm3+, 1% Tm3+ phosphors varied from blue to orange-red continuously when the temperature gradually increased. We could roughly estimate the temperature change by the luminescence color. The test of the temperature cycle showed that the repeatability of temperature measurement using FIR was good. Overall, the Gd2Ti2O7: Sm3+, Tm3+ phosphors had good application prospects.