EPR and Optical Properties of UV-B Radiation-Emitting Gd3+-Doped BaLa2ZnO5 Host Prepared by Sol–Gel Method

A series of trivalent gadolinium ion-doped BaLa2ZnO5 phosphors was prepared by the sol–gel technique. Phase purity and crystal structure were confirmed by the Rietveld refinement. The morphology of the sample was studied by scanning electron microscopy. The effect of Gd3+ concentration on the luminescence of the BaLa2−xGdxZnO5 (x = 0.01 ≤ x ≤ 0.15) samples was investigated by photoluminescence spectra. Under excitation at 273 nm, all the samples showed ultraviolet emission near 314 nm, generated by the 6P7/2 → 8S7/2 transition of Gd3+ ions. It was found that the emission intensity increased with the concentration of Gd3+ ions up to 0.15 mol without concentration quenching. The electron paramagnetic resonance spectra of the Gd3+ ion-doped BaLa2ZnO5 phosphors indicated that the dopant ions occupied slightly distorted La3+ sites in the host lattice. Both the PL and EPR studies describe the excited and ground-state features of Gd3+ ions in the BaLa2ZnO5 host lattice.