For achieving well‐performing optical thermometry, a new type of dual‐mode optical thermometer is explored based on the valley‐to‐peak ratio (VPR) and fluorescence lifetime of Eu ³⁺ emissions in the ZrO ₂ :Eu ³⁺ nanocrystals with sizes down to 10 nm. In the VPR strategy, the intensity ratio between the valley (600 nm) generated by the emission band overlap and the 606 nm peak ( ⁵ D ₀ → ⁷ F ₂ ), which is highly temperature sensitive, is employed, giving the maximum relative sensing sensitivity ( S _r ) of 1.8% K ⁻¹ at 293 K and good anti‐interference performance. Meanwhile, the 606 nm emission exhibits a temperature‐dependent decay lifetime with the highest S _r of 0.33% K ⁻¹ at 573 K, which is due to the promoted nonradiative relaxation with temperature. These results provide useful information for constructing high‐performance dual‐mode optical thermometers, which may further stimulate the development of photosensitive nanomaterials for frontier applications.

Luminescence thermometry, an important technique for remote temperature readout, requires the exploitation of new thermometric strategies to improve sensing properties. Herein, we propose a novel single band ratiometric thermometric strategy based on the dependence of luminescence thermal quenching behavior on the excitation wavelength in a Pr³⁺:Gd₂ZnTiO₆ phosphor. With the increase of temperature, the ³P₀ → ³H₄ emission of Pr³⁺ weakened sharply upon the Pr³⁺–Ti⁴⁺ intervalence charge transfer (IVCT) excitation (λ_ex = 340 nm), whereas it was insensitive to temperature under the ³H₄ → ³P₂ excitation (λ_ex = 451 nm). Thus, the intensity ratio of the single ³P₀ emission at the two distinct excitation wavelengths (451 and 340 nm) could be exploited for optical thermometry. Excellent absolute sensing sensitivity (S_a-max = 1.74 K⁻¹), relative sensitivity (S_r-max = 3.64% K⁻¹) and thermal uncertainty (δT_min = 0.14 K) were realized, which were superior to those of many other thermometric phosphors. This strategy was proved to be also valid for other Pr³⁺ doped oxides containing IVCT states, such as Pr³⁺:Gd₂MgTiO₆, Pr³⁺:LiLaMgWO₆ and Pr³⁺:La₂ZnTiO₆. These results could provide useful information for developing innovative luminescent thermometers with high performance.