The luminescence and structural properties of layered Y₂O₃:Eu³⁺ phosphors, synthesized by a simple evaporation method followed by thermal annealing at temperatures up to 1100 °C, are described for a europium doping concentration of 4.3 at. % as determined by energy dispersive spectroscopy. The intense luminescence emission spectra of these samples are associated with the characteristic intra-electronic energy levels of Eu³⁺ ion transitions. The dominant emission peak is at 611 nm, corresponding to the ⁵D₀ to ⁷F₂ transition, and the dominant excitation peak is at λ_exc = 245 nm. A layered morphology was observed in these phosphors by both transmission and scanning electron microscopy studies. The samples have a cubic crystalline structure.

The optical, structural, and electrical characteristics of aluminum oxide thin films deposited by pulsed ultrasonic sprayed pyrolysis are reported. The films are deposited on crystalline silicon at temperatures from $400\text{to}550°\mathrm{C}$ using a chemical solution of aluminum acetylacetonate, as source of aluminum, and $N$ , $N$ -dimethylformamide, as solvent. A ${\mathrm{H}}_2\mathrm{O}–\mathrm{N}{\mathrm{H}}_4\mathrm{O}\mathrm{H}$ mist is supplied simultaneously during deposition to improve the films’ properties. The results showed that the properties of the as deposited films depended strongly on the number of pulses used and on the substrate temperature. The thickness of the films is under $300\mathrm{\AA }$ and the best films’ properties showed an index of refraction close to 1.6 and a root mean square surface roughness of about $7.5\mathrm{\AA }$ in average. Infrared spectroscopy shows that $\mathrm{Si}{\mathrm{O}}_2$ is observed at the interface with silicon of the ${\mathrm{Al}}_2{\mathrm{O}}_3$ films and seemed to play, as expected, a dramatic role in the electrical characteristics of the interface. Films with a dielectric constant higher than 8 and an interface trap density at midgap in the ${10}^{10}{\mathrm{eV}}^{-1}{\mathrm{cm}}^{-2}$ range are obtained. Films deposited with three pulses and at $550°\mathrm{C}$ are able to stand an electric field up to $4\mathrm{MV}∕\mathrm{cm}$ .