In this report we present synthesis and thermographic properties of Dy-activated Na_0.25K_0.25Bi_0.48Dy_0.02TiO₃ powder. The material is prepared by a solid-state reaction using TiO₂, Bi₂O₃, Na₂CO₃, K₂CO₃ and Dy₂O₃ as precursor materials. Starting powders were ball milled in ethanol for 12 h, then dried and calcined at 850°C for 2 h. Subsequently, the obtained powder was additionally milled in ethanol for 12 h, and finally sintered at 850°C for 4 h. X-ray diffraction measurement revealed that NKBT sample exhibits a tetragonal perovskite structure, belonging to the P4bm space group, without impurities. Emission spectra showed characteristic bands of Dy³⁺ ions with pronounced emission originating from f–f electronic transitions. A dominant band in the blue region with maximum at around 477 nm originates from magnetic-dipole ⁴F_9/2→⁶H_15/2 transition, while another one in the yellow region peaking at around 574 nm comes from electric-dipole ⁴F_9/2→⁶H_13/2 transition. A small intensity high-energy band centered at around 457 nm originating from ⁴I_15/2→ ⁶H_15/2 transition, provided the possibility to use this type of emitting material as temperature sensor in luminescence thermometry. Temperature readings from material’s luminescence emission were acquired via relative luminescence emission intensity measurements (LIR). This approach uses the ratio of intensities of two specific emission bands, in this case emissions from ⁴F_9/2 and ⁴I_15/2 excited states to the ⁶H_15/2 ground state [1, 2]. With this material, relative sensitivity of about 2% K^-1 and temperature resolution of 0.5 K of thermometry have been achieved.

References:

1. Ž. Antić, M. D Dramićanin, K. Prashanthi, D. Jovanović, S. Kuzman, T. Thundat, "Pulsed Laser Deposited Dysprosium-Doped Gadolinium–Vanadate Thin Films for Noncontact, Self-Referencing Luminescence Thermometry", Advanced Materials, Volume 28(35), 7745-7752 (2016).
2. M. D Dramićanin, "Sensing temperature via downshifting emissions of lanthanide-doped metal oxides and salts. A review", Methods and Applications in Fluorescence, Volume 4(4), 042001(23 pp) (2016).