Judd‐Ofelt analysis and optical properties of Eu³⁺‐doped GdPO₄ phosphors synthesized by combustion method

The Eu 3+ ‐doped GdPO 4 nanoparticles were prepared via a straightforward combustion method using urea as fuel and nitrates as a precursor. X‐ray powder diffraction patterns, infrared spectrum (IR), HR‐TEM, photoluminescence (PL), phonon sideband and photoluminescence excitation (PLE) were researched. There is a phase transition from the hexagonal phase into the monoclinic phase when the calcined temperature is over 700 °C. All of phosphors have similar morphology and the average diameters for nanoparticles are 20–30 nm. Under the excitation at 273 nm, GdPO 4 :Eu 3+ powders showed red emission bands originating from the 5 D 0 – 7 F J ( J = 1, 2, 3 and 4) transitions of Eu 3+ . The orange‐red emission ( 5 D 0 – 7 F 1 transition) is dominated because the Eu 3+ ions exist with inversion symmetry in the lattice. The study suggests that the optimal Eu 3+ ions concentration is 5 mol%. In addition, the second order crystal field parameter (B 20 ) and the influence of concentration of Eu 3+ ions on decay time are also mentioned, the intensity parameters (Ω 2,4,6) and quantum efficiency were determined based on Judd‐Ofelt theory.