Pr^{3 +}-Based Fluorescent TiO₂ Split Ring Resonator-Like Crystalline Microstructures

We demonstrate the successful incorporation of luminescent Pr³⁺ ions into TiO₂ split ring resonator-like microcrystalline structures embedded in SrTiO₃, which are obtained by directional solidification of the SrTiO₃–TiO₂ eutectic. Raman and fluorescence spectroscopy reveal that Pr³⁺ incorporates into both component phases, the spectral features of each compound being spatially separated. Confocal spectroscopy maps are found to correlate well to the composition and crystal orientation of the heterostructures. The results support the feasibility of engineering trivalent rare-earth ion doped self-organized oxide–oxide eutectic structures as potential candidates for photo-electrochemical or photoactive devices based on novel TiO₂ structures.