Abstract <p>The CeF₃:Tb³⁺ (1%), CeF₃, LaF₃:Tb³⁺ (1%), CeF₃:LaF₃:Tb³⁺ (1%), LaF₃:Ce³⁺ (5%), LaF₃:Ce³⁺&#xa0;(5%):Tb³⁺ (1%) nanoparticles were synthesized via co-precipitation method. Nanoparticles of mononuclear and core-shell structures had diameters of 70 and 200 nm, respectively, and a hexagonal phase. Spectral characterization of the samples was carried out in the temperature range of 80–430 K with excitation at a wavelength of 266 nm. The luminescence band intensities of Ce³⁺ and Tb³⁺ cerium ions were also calculated as a function of temperature for all samples. It was shown that the structures with spatially separated Ce³⁺ and Tb³⁺ ions have the highest temperature sensitivity: CeF₃:LaF₃:Tb³⁺ (1%) core-shell and a mechanical mixture of CeF₃ and LaF₃:Tb³⁺ (1%) powders. Due to the spatial separation of Ce³⁺ and Tb³⁺ ions and the exclusion of resonant energy transfer between them, it was concluded that for the studied nanoparticles, the main contribution to the temperature sensitivity is the different dependence of the luminescence intensity of Ce³⁺ ions on temperature compared to the similar dependence of Tb³⁺ ions, which makes it possible to measure the temperature based on the ratio of the integral intensities of Ce³⁺ and Tb³⁺.</p>