抄録
Nanocrystalline gadolinium niobate, GdNbO4 with fergusonite structure was directly formed from the precursor solution mixtures of GdCl3 and NbCl5 under weakly basic conditions at temperatures higher than 210°C for 5 h in the presence of aqueous ammonia via hydrothermal route. The as-prepared GdNbO4 nanocrystals and those after heating at 1000–1300°C showed UV-blue and broad-band emission centered at 435 nm under excitation at 266 nm due to the blue recombination luminescence, associated with charge transfer transitions involving the tetrahedral NbO4 group. The fergusonite-type complete solid solution nanocrystals having good luminescence in the red spectral region in the GdNbO4–EuNbO4 system were directly formed under hydrothermal conditions at 240°C. The photoluminescence spectra of the as-prepared nanocrystalline solid solutions containing europium under excitation at 240 nm are responsible for the characteristic weak orange luminescence (592 nm) and strong red luminescence (611 nm), associated with 5D0 → 7F1 and 5D0 → 7F2 transitions, respectively. In the composition Gd0.80Eu0.20NbO4, the maximum intensity of red emission was observed and the emission was even more enhanced via heating at 1300°C.
