Effect of calcination temperature on phase evolution and photoluminescent properties of GdPO4:Eu3+ nanoparticle phosphors synthesized by combustion method

Abstract

Eu3+ -doped GdPO4 nanoparticles were synthesized by a straightforward combustion method using urea as fuel and metal nitrates as precursors. Structures, morphologies and photoluminescent properties of the synthesized samples were studied by X-ray diffraction, scanning electron microscopy and photoluminescent spectroscopy. There are two types of crystal structures formed during the annealing process: hexagonal GdPO4.H2O and monoclinic GdPO4. The former can be found at low annealing temperatures (300-500°C) while the latter can be obtained at higher annealing temperatures (700-900°C). The average diameters for nanoparticles are 20-30 nm. Under the excitation at 273 nm, both GdPO4.H2O:Eu3+ and GdPO4:Eu3+ powders showed red emission bands originating from the 5D0 - 7FJ (J = 1, 2, 3 and 4) transitions of Eu3+. Their PL intensity and crystal structures exhibit a similar behavior as a function of the annealing temperature.