Photoluminescence investigations on a novel green-emitting phosphor Ba3Sc(BO3)3:Tb3+ using synchrotron vacuum ultraviolet radiation

Abstract

Vacuum ultraviolet (VUV) spectroscopic properties of undoped and Tb³⁺-doped Ba₃Sc(BO₃)₃ were investigated by using synchrotron radiation. The Tb³⁺-doped Ba₃Sc(BO₃)₃ sample crystallized in a flower-like shape even was synthesized at 1100 °C. Upon VUV excitation, Ba₃Sc(BO₃)₃ exhibited an intrinsic broad UV emission centered at 336 nm, which results from radiative annihilation of self-trapped exciton (STE) that may presumably be associated with band-gap excitations or molecular transitions within the BO₃³⁻ group. The maximum host absorption for Ba₃Sc(BO₃)₃ was found at about 180 nm. Upon doping of Tb³⁺ ions into Ba₃Sc(BO₃)₃, an efficient energy transfer from the host excitations to Tb³⁺via STE emission was observed, showing host sensitization of Tb³⁺ occurs. The energy transfer from host to Tb³⁺via STE emission in Ba₃Sc(BO₃)₃:Tb³⁺ was studied as a function of temperature and Tb³⁺ doping concentration. It has been demonstrated that the energy transfer efficiency was increased with either increasing temperature or Tb³⁺ doping concentration. In the case of temperature dependent energy transfer, the energy transfer from the STE to Tb³⁺ is thermally activated, probably due to exciton mobility, while in the case of concentration dependent energy transfer, the energy transfer from the STE to Tb³⁺ is promoted due to a closer distance between the STE and Tb³⁺ at high Tb³⁺ concentration.