Photoluminescent ZrO₂:Tb³⁺thin films synthesized by USP technique using a metal-organic precursor

Photoluminescent ZrO2 and ZrO2:Tb3+ thin films were synthesized from metal-organic precursor, zirconium acetylacetonate [Zr(C5H7O2)4], using Ultrasonic Spray Pyrolysis method. These thin films were deposited on Corning glass substrates at several deposition temperatures. ZrO2 and ZrO2:Tb3+ (X a/o) films were characterized by X-ray diffraction to identify the crystalline structure; results showed tetragonal phase of zirconia; with a crystalline size of approximately 4 nm according to Scherrer's formula. Also, SEM micrographs revealed that surface morphology of these films is very flat. Chemical composition microanalysis showed presence of oxygen and zirconium as major species. Analysis by Infrared spectroscopy demonstrates that 900 and 760 nm bands correspond to presence of ZrO2. In addition, these films showed optical transmittances from 75 to 98 % in the visible range. Photoluminescent features varied as a function of excitation wavelength; when excited at λ ex = 286 nm strong green emission is observed, which is associated to electronic transitions 5D4 → 7Fn (n = 6, 5, 4, 3) corresponding to Tb3+ ions. Excitation with λ ex = 336 nm exhibits spectra with simultaneous emissions from host lattice and Tb3+ ions; here, observed color was blue-green.