Tingming Jiang

Effects of crystal field on photoluminescence properties of Ca2Al2SiO7:Eu2+ phosphors

Abstract A series of single-phased Ca2Al2SiO7:Eu2+ phosphors were synthesized by the solid-state reaction. Their structure and photoluminescence properties were investigated by the X-ray powder diffraction (XRD) and excitation and emission spectra in detail. The emission spectra of Ca2Al2SiO7:Eu2+ phosphors consisted of blue and green band located at 419 and 542 nm, respectively. The relative intensities of the blue and green emission changed with Eu2+ concentration and were sensitive to the excitation wavelength. The unique photoluminescence property originated from the 4f7→4f65d transition of Eu2+ at different energy levels, on which the effect of the crystal field strength was considered to be tailed by adjusting the host composition.

Improvement of the energy transfer from Ca3SnSi2O9 host to rare-earth ions with the assistance of oxygen vacancies

The blue emission of Ca3SnSi2O9 was identified to arise from the recombination of electrons and holes via intrinsic oxygen vacancy defects using photoluminescence spectra measurements, density functional theory calculations, and thermoluminescence analysis. A significant enhancement in the photoluminescence intensity of the blue emission was observed in samples of Ca3SnSi2O9 co-doped with fluorine, which was attributed to the increased number of oxygen vacancy defects produced in Ca3SnSi2O9. Most importantly, the improvement of the photoluminescence intensity of Dy3+ demonstrated that energy transfer from the Ca3SnSi2O9 host to the activators became more effective when fluorine was co-doped. It indicates that fluorine could be introduced into the Ca3SnSi2O9 host by this approach, which produced more oxygen vacancies and contributed to the improved photoluminescence performance of the activators.