RESUMEN
Nowadays, orthovanadates are studied because of their unique properties for optoelectronic applications. In this work, the LuVO4:Eu3+, Bi3+ films were prepared by the sol-gel method, using a new simple route, and deposited by the dip-coating technique. The obtained films are transparent, fracture-free, and homogenous. The sol-gel process was monitored by Fourier-transform infrared spectroscopy (FTIR), and according to X-ray diffraction (XRD) results, the crystal structure was tetragonal, and films that were highly oriented along the (200) low-energy direction were obtained. The morphological studies by scanning electron microscopy (SEM) showed uniformly distributed circular agglomerations of rice-like particles with nanometric sizes. The luminescence properties of the films were analyzed using a fixed concentration of 2.5 at. % Eu3+ and different concentrations of Bi3+ (0.5, 1.0, and 1.5 at. %); all the samples emit in red, and it has been observed that the light yield of Eu3+ is enhanced as the Bi3+ content increases when the films are excited at 350 nm, which corresponds to the 1S0â3P1 transition of Bi3+. Therefore, a highly efficient energy transfer mechanism between Bi3+ and Eu3+ has been observed, reaching up to 71%. Finally, it was established that this energy transfer process occurs via a quadrupole-quadrupole interaction.
RESUMEN
The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN) co-doped with the La3+-Mn4+ and Eu3+-Fe3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR) studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La3+-Mn4+ and Eu3+-Fe3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications.