Vis-NIR luminescence of GdVO4:RE3+/SiO2 (RE = Er3+, Yb3+, Nd3+) nanophosphors enhanced by γ-radiation

Abstract

γ-radiation effect on structure, morphology and optical behaviour of GdVO4:RE3+/SiO2 (RE3+ = Er3+, Yb3+, Nd3+) nanophosphors has been evaluated. The synthesized products were examined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Photoluminescence spectra (PL). After photoexcitation of GdVO4:Er3+/SiO2, GdVO4:Yb3+/SiO2, GdVO4:Nd3+/SiO2 at 462, 487 and 532 nm, the respective rare-earth ions from phosphors emits red and NIR luminescence at 617 (2P3/2→ 4F9/2) and 690 nm (4F9/2→ 4I15/2); 640 (5F5/2→ 5I8/2) and 731 nm (5F4/2→ 5I7/2); 680 (4F9/2→ 4I9/2) and 798 nm (4F5/2→ 4I9/2). It was observed that the luminescence intensity had escalated on increasing the RE3+ content from 1 mol% to 5 mol%. Furthermore, after γ-irradiation at 150 and 300 kGy, the luminescence intensity had gone up 2–5 folds and 5–9 folds, respectively. On the other hand, the optical band gap was observed to have decreased with increasing luminescence intensity before and γ-irradiation. This enhanced red and NIR luminescence is very useful for LEDs, display and biomedical applications.