Plasma-Generated Luminescent Coatings: Innovations in Thermal Sensitivity and Corrosion Resistance

The strategic design of traditional coating materials has long been pivotal in broadening their range of applications. In this work, europium-doped TiO₂ coatings are grown in situ on the surface of titanium substrate using plasma electrolytic oxidation technology. The core reaction took no more than five minutes. Incorporating europium into the coating preserved the inherent corrosion resistance of PEO coatings while imparting anticipated thermal-sensitive luminescence capabilities. The intrinsic emission of TiO₂ and the characteristic emission of Eu³⁺ (⁵D₀ → ⁷F₂) are employed as the self-reference for the LIR thermometry. The absolute and relative temperature sensitivity of the coating reached 0.0087 K⁻¹ and 0.739% K⁻¹, respectively. Notably, the coating exhibited a signal discriminability of up to 5100 cm⁻¹ and a temperature uncertainty of only 0.18 K, which is comparable to some TiO₂: Eu nanoparticles. The ingenious fusion of corrosion resistance and thermal-sensitive luminescence of the coating not only makes it a classic protective structure but also facilitates its applicability to diverse scenarios, including optical thermometry in extreme environments.