Terbium-doped gadolinium orthovanadate (GdVO4:Tb3+), orthophosphate monohydrate (GdPO4·H2O:Tb3+) and orthovanadate–phosphate (GdV,PO4:Tb3+) powder phosphors were synthesized using a solution combustion method. X-Ray diffraction analysis confirmed the formation of crystalline GdVO4, GdPO4·H2O and GdV,PO4. Scanning electron microscopy images showed that the powder was composed of an agglomeration of particles of different shapes, ranging from spherical to oval to wire-like structures. The chemical elements present were confirmed by energy dispersive spectroscopy, and the stretching mode frequencies were determined by Fourier transform infrared spectroscopy. UV–visible spectroscopy spectra showed a strong absorption band with a maximum at 200 nm assigned to the absorption of VO43− and minor excitation bands assigned to f → f transitions of Tb3+. Four characteristic emission peaks were observed at 491, 546, 588 and 623 nm, and are attributed to 5D4 → 7Fj (j = 6, 5, 4 and 3). The photoluminescent prominent green emission peak (5D4 → 7F5) was centred at 546 nm. The structure and possible mechanism of light emission from GdV1−xPxO4:% Tb3+ are discussed.
- combustion synthesis
- orthovanadate phosphates