A single-phased tunable emission phosphor MgY2Si3O10: Eu3+, Bi3+ with efficient energy transfer for white LEDs†
A novel single-phased tunable emitting phosphor MgY2Si3O10: Bi3+, Eu3+ has been synthesized by a conventional high temperature solid-state method. X-ray diffraction (XRD), photoluminescence emission and excitation spectra were utilized to characterize the as-synthesized samples. Under UV-light pumping, MgY2Si3O10: Bi3+ showed characteristic blue emission corresponding to the 3P1→1S0 transition of Bi3+ ions, and MgY2Si3O10: Eu3+ showed characteristic red emission corresponding to the 5D0→7FJ (J = 1, 2, 3, 4) transition of Eu3+ ions. Spectra indicate that Bi3+ ions occupy two nonequivalent sites in the MgY2Si3O10 matrix, namely, Bi3+(I) and Bi3+(II). The two sites (Bi3+(I) and Bi3+(II)) exhibit broad emission peaks at 411 nm and 490 nm, respectively. Efficient energy transfer between these two Bi3+ sites has been proven using the spectra. The spectral overlap between the emission spectrum of Bi3+ and the excitation spectrum of Eu3+ allows for resonance-type energy transfer to occur from Bi3+ to Eu3+. The efficient energy transfer from Bi3+ to Eu3+via a dipole–quadrupole interaction mechanism is significantly demonstrated by comparing experimental data with theoretical calculations. According to the concentration quenching-method, the critical distance of energy transfer from Bi3+ to Eu3+ is calculated to be 13.2 Å. As it is a new phosphor, CIE coordinates and CCT temperature, in addition to efficient energy transfer have been also investigated in detail. White light emission for MgY2Si3O10: n Bi3+, m Eu3+ can be realized through controlling the concentrations of Bi3+ and Eu3+. All of the results indicate that MgY2Si3O10: n Bi3+, m Eu3+ is a potential phosphor for white light UV-LEDs.