Enhanced fluorescence of La${}^{3+}$, Gd${}^{3+}$ doped EuW${}_{10}$ for temperature sensing performance

Using the luminescent properties of temperature-sensitive paints (TSPs) to monitor temperature is a new type of temperature measurement technology. Herein, Na${}_9$[EuW${}_{10}$O${}_{36}$](EuW${}_{10}$) molecules were doped with non-fluorescent rare earth metal ions (La${}^{3+}$ and Gd${}^{3+}$) to prepare Na${}_9$[Eu${}_x$La${}_{1-x}$W${}_{10}$O${}_{36}$](Eu${}_x$La${}_{1-x}$W${}_{10}$) and Na${}_9$[Eu${}_x$Gd${}_{1-x}$W${}_{10}$O${}_{36}$](Eu${}_x$Gd${}_{1-x}$W${}_{10}$) probe molecules. The doping of non-fluorescent rare earth metal ions (La${}^{3+}$ and Gd${}^{3+}$) will not change the structure of the parent EuW${}_{10}$. As the relative content of La${}^{3+}$ ions increasing, the luminescent intensity of the Eu${}_x$La${}_{1-x}$W${}_{10}$ series decreases non-monotonically; as the relative content of Gd${}^{3+}$ ions increasing, the luminescent intensity of Eu${}_x$Gd${}_{1-x}$W${}_{10}$ series decreases monotonically. Subsequently, Eu${}_x$La${}_{1-x}$W${}_{10}$ and Eu${}_x$Gd${}_{1-x}$W${}_{10}$ as probe molecules were added into methyl methacrylate (MMA) to obtain temperature-sensitive paints via polymerization process. In the range of 50 °C to 100 °C, the maximum relative sensitivity of temperature-sensitive paints EuW${}_{10}$/PMMA, Eu${}_{0.9}$La${}_{0.1}$W${}_{10}$/PMMA and Eu${}_{0.7}$Gd${}_{0.3}$W${}_{10}$/PMMA can reach 1.27 % °C${}^{-1}$, 1.43 % °C${}^{-1}$, 1.42 % °C${}^{-1}$, respectively. This study indicates that the temperature sensing characteristics can be enhanced by doping EuW${}_{10}$ with non-fluorescent rare earth ions (La${}^{3+}$, Gd${}^{3+}$), which can be promising materials used in more areas with high-precision temperature measurements. (© 2021 Wiley‐VCH GmbH)