Tb3+-, Eu3+-activated, and Eu3+/Tb3+-coactivated oxyfluoride borogermanate scintillating glasses with the density of about 6.50g/cm(3) were successfully synthesized by a melt-quenching method. The structure and optical properties including transmittance, photoluminescence (excitation and emission spectra), photoluminescence decay, and X-ray excited luminescence behaviors were studied in detail. Our results reveal that the energy-transfer efficiency from Tb3+ to Eu3+ ions increases with an increase in Eu3+ concentration. The energy-transfer mechanism is also discussed by Dexter's and Reisfeld's semiexperimental methods.