Particle morphology and luminescence properties of green emitting Ba2SiO4:Eu2+ through a hydrothermal reaction route

Green-emitting (Ba0.97Eu0.03)2SiO4 phosphors of different morphologies and particle sizes were prepared by varying the conditions of hydrothermal synthesis. Single-phase powders were obtained at 250 °C and autogeneous pressure followed by post annealing at 900 °C for 1 h. The ethanol/water ratio, hydrothermal reaction time, NaOH/Ba2+ ratio and silicon precursor strongly influence the particle size and morphology. The particle size, having spherical or needlelike shapes, ranges from 200 nm to 3 μm, depending on those parameters. These phosphors show strong absorption in the near UV range and the photoluminescence emission spectra consist of a strong broad green band centered around 514 nm. Furthermore, the emission intensities are dependent on the ethanol to water ratio, and 55-79% of that of micron-sized powders with a quantum efficiency of 94%.