Photo- and radioluminescence characteristics of bismuth germanate nanoparticles by sol–gel and pressure-assisted combustion synthesis

Abstract

Bismuth germanate (Bi4Ge3O12, BGO) nanophosphors have been synthesized by sol–gel and pressure-assisted combustion synthesis techniques. Sol–gel or combustion synthesized precursors for BGO were post-annealed by a fast or slow thermal treatment, both in ambient air. The microstructure of synthesized samples under fast annealing consists of spherical shape nanoparticles with an average diameter size of 4nm, whereas those prepared by the slow thermal treatment have faceted surface with diameter in the range of 2–6nm. Both samples yield strong bluish-white luminescence under UV excitation of 4.3eV (288nm). The luminescence band is composed of a double-peak suggesting a contribution from two fundamental emissions at 2.83eV (440nm) and 2.43eV (510nm). The powders excited by X-ray of 7keV from a synchrotron source showed the typical radioluminescence of BGO. These nanophosphors yield similar scintillating properties as BGO single crystal.