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

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 4 nm, whereas those prepared by the slow thermal treatment have faceted surface with diameter in the range of 2–6 nm. Both samples yield strong bluish-white luminescence under UV excitation of 4.3 eV (288 nm). The luminescence band is composed of a double-peak suggesting a contribution from two fundamental emissions at 2.83 eV (440 nm) and 2.43 eV (510 nm). The powders excited by X-ray of 7 keV from a synchrotron source showed the typical radioluminescence of BGO. These nanophosphors yield similar scintillating properties as BGO single crystal.

► Bi4Ge3O12 luminescent nanoparticles were synthesized by combustion synthesis and sol–gel. ► The nanophosphors yield strong bluish-white luminescence under UV (λ = 288 nm) excitation. ► The luminescence band is composed of two emissions centered at λ = 440 nm and λ = 510 nm. ► The best method to prepare high luminescence Bi4Ge3O12 nanophosphors is sol–gel.