Luminescent properties and energy transfer of Gd3+/Eu3+ co-doped cubic CaCO3

Gd3+ and Eu3+ ions co-doped CaCO3 nanoparticles have been successfully synthesized via carbonization method. The emission spectra of co-doped CaCO3 phosphors in the range of VUV-vis spectral were studied. The results reveal that the co-doped CaCO3 phosphors show intense red emission in the VUV range because of the Gd3+ ions as sensitizers. The energy transfer process from Gd3+ to Eu3+ in CaCO3:Gd3+/Eu3+ phosphors was investigated and discussed in terms of the luminescence spectra and the decay curves, which demonstrated that the energy transfer of Gd3+→Eu3+ is efficient. The mechanism of energy transfer from Gd3+ to Eu3+ is a resonant transfer, in which electric dipole-dipole interaction plays a leading role. Furthermore, the effect of doping concentration of Eu3+ ions on the energy transfer efficiency was also investigated. From the photoluminescence (PL) spectra, it was also found that the incorporation of Na+ ions into CaCO3:Gd3+/Eu3+ could lead to a remarkable increase of luminescent intensity due to the charge compensation.