CAJ | 학술논문

A novel green-emitting phosphor, Eu2+-doped Ca2-x/2Si1-xPxO4 (0.25≤x≤0.30), was prepared through a conventional solid-state reaction. X-ray diffraction (XRD), photoluminescence (PL) and decay studies were employed to characterize the sample, which was assigned to P63mc space group in the hexagonal system. The effect of P-doping on theα-Ca2SiO4 was studied and P2O5 broken down by the raw material of (NH4)2HPO4 played an important role in stabilizingα-Ca2SiO4 which can only be stable at high tem-perature. The XRD patterns of the Ca2-x/2Si1-xPxO4 host were found pure and optimized when the mole fraction of P2O5 was 14.5%. The diffuse reflectance spectra of the Ca1.855Si0.71P0.29O4 and Ca1.845Si0.71P0.29O4:0.01Eu2+covered the spectral region of 230-400 nm, implying that the phosphor was suitable for UV or near-UV LED excitation. The phosphor could be effectively excited in the near UV region with the maximum at 372 nm. The emission spectrum of the Ca1.845Si0.71P0.29O4:0.01Eu2+phosphor showed an asymmet-rical single intensive band centered at 513 nm, which corresponded to the 4f65d1→4f7 transition of Eu2+. Eu2+ions might occupy two types of Ca2+sites in the Ca1.855Si0.71P0.29O4 lattice and form two corresponding emission centers, which led to the asymmetrical emis-sion of Eu2+in Ca1.855Si0.71P0.29O4. The effects of Eu2+-doped concentration in Ca1.855-xSi0.71P0.29O4:xEu2+on the PL were also dis-cussed, the optimum doping concentration of Eu2+was 1 mol.%and the critical distance of the energy transfer was also calculated by the concentration-quenching method. The non-radiative energy transfer between Eu2+seemed to be caused by the multipole-multipole interaction. The fluorescence lifetime of Eu2+was found to be 0.55711μs. The results suggested that these phosphors might be prom-ising candidates used for near UV light excited white LEDs.