Preparation of Photoluminescent Zr-Eu Compound Films Based on Electrodeposited 3D Zirconium Oxyfluoride Films

Abstract Photoluminescent europium-zirconium compound films were prepared by immersing electrodeposited 3D zirconium oxyfluoride films comprising aggregates of sword-type leaf-like units, in a europium nitrate aqueous solution at 323 K. Characterization of the as-immersed films using X-ray diffraction analysis and scanning transmission electron microscopy revealed the deposition of EuF3 on the surface of the leaf-like units. Analysis of the films calcined at 773 K in air employing Raman scattering spectroscopy suggested that the films were composed of rhombohedral EuOF and Eu3+-doped tetragonal ZrO2. The red photoluminescence of the films at room temperature originating from the 4f–4f transitions of Eu3+ was investigated in relation to the site symmetry of Eu3+ in the crystalline phase. The red photoluminescence properties of the films were improved by calcination, which intensified the peak of the 5D0 → 7F2 transition at ~610 nm, called as the electric dipole transition (EDT). The EDT emission intensity of the calcined films increased with increasing Eu3+ concentration in the immersion solution, which was attributed to the dominant crystalline growth of rhombohedral EuOF showing lower Eu3+ site symmetry compared with Eu3+-doped tetragonal ZrO2.