Structure Refinement and One-Center Luminescence of Eu3+ Activated ZnBi2B2O7 under UV Excitation

A series of Eu3+-activated red phosphors ZnBi2B2O7:xEu3+ were synthesized by high temperature solid-state reaction method. Rietveld refinement on the powder X-ray diffraction (XRD) data was performed to study the local crystal environment of Eu3+ in ZnBi2B2O7 host. The refinement results disclose that the doped Eu3+ do not change the host structure. Although two different cation sites are available, the doped Eu3+ is inclined to occupy Zn site instead of Bi site. This indicates that there is only one luminescent center when Eu3+ is doped into ZnBi2B2O7 phosphor, which is further confirmed by the luminescence properties of ZnBi2B2O7:xEu3+. The influences of the doping concentration and the excitation wavelength on the one-center luminescence of Eu3+ in ZnBi2B2O7 are discussed along with the decay characteristics. Based on the temperature-dependent PL spectra, the fast decrease of emission intensity with the increase of temperature is due to the non-radiative relaxation.