Non-contact thermometry with Dy³⁺ doped Gd₂Ti₂O₇ nano-powders

The performance of Dy³⁺ doped Gd₂Ti₂O₇ nano-powders for luminescence temperature sensing was tested over a temperature range from 293 to 443 K. The Dy³⁺ ions were incorporated into Gd₂Ti₂O₇ nanocrystals using a hydrolytic sol–gel route. Microstructural characterization of the obtained material was performed using transmission electron microscopy and X-ray diffraction measurements. Luminescence spectra of Dy³⁺ doped Gd₂Ti₂O₇ nano-powders consists of two distinct spectral regions: the high-energy region associated with the trap emission of the Gd₂Ti₂O₇ host and the low-energy region with well-resolved emission peaks of the Dy³⁺ ions. The ratio between intensities of two Dy³⁺ emission lines, as well as the ratio between intensities of trap emission of host and Dy³⁺ emission show strong temperature dependence and are tested for temperature sensing. In both cases, ratiometric measurements provide comparable quality of temperature sensing, and when they are combined the relative sensor sensitivities were found to be higher than 0.9% K⁻¹ over given temperature range. The fluorescence quenching of Dy³⁺ ions was discussed in terms of simple theoretical models. - Highlights: • Dy³⁺ doped Gd₂Ti₂O₇ nanoparticles can serve as probes for luminescence thermometry. • Trap emission of host can be an excellent standard for luminescence thermometry. • Temperature can be measured over 293–443 K range with sensitivity reaching 0.9% K⁻¹.