Regulating thermometric properties of single-band ratiometric luminescent thermometers based on Eu3+-activated Y2W3O12·3H2O nanoparticles via controlling doping content and excitation model

Series of Eu ³⁺-activated Y ₂W ₃O ₁₂·3H ₂O nanoparticles were designed to realize high-sensitive optical thermometry. The resultant nanoparticles can emit bright visible emission from Eu ³⁺ upon the excitation of 296 nm (charge-transfer state (CTS) of O ^2- → W ⁶⁺), 394 nm (ground state absorption (GSA)) and 536 nm (excitation state absorption (ESA)), of which the fluorescence intensities were influenced by dopant content. The negative thermal expansion properties of studied nanoparticles were clarified via temperature-dependent X-ray diffraction patterns. Moreover, the thermal quenching behaviors of final products were also investigated through temperature-related emission spectra. Specifically, upon the CTS and GSA processes, the developed nanoparticles underwent significant thermal quenching effect, whereas the thermally enhanced luminescence was observed under ESA process. Herein, through using the single-band ratiometric (SBR) method to investigate the fluorescence intensity ratio of the red emission from ⁵D ₀ → ⁷F ₂ transition of Eu ³⁺ at high temperature, the thermometric properties of prepared nanoparticles were studied. It was found that maximum absolute and relative sensitivities of Eu ³⁺-activated Y ₂W ₃O ₁₂·3H ₂O nanoparticles reached up to 0.061 and 4.944 % K ⁻¹, respectively, and they can be regulated by changing Eu ³⁺ dopant and SBR models ( i.e., ESA+CTS and ESA+GSA combinations), realizing high-sensitive optical thermometry. Our findings may provide some guidelines for manipulating the thermometric properties of rare-earth ions activated materials and developing new SBR luminescence thermometers.