Enhanced Luminescence of BPO4 by Mixing with SiO2 and Al2O3

In this paper, BPO 4 - x SiO 2 ( x: SiO 2 /BPO 4 molar ratio, 0−70%) and BPO 4 - x Al 2 O 3 ( x: Al 2 O 3 /BPO 4 molar ratio, 0−20%) powder samples were prepared by the Pechini-type sol−gel (PSG) process using glycerol and poly(ethylene glycol) as additives. The structure and optical properties of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), diffuse reflection spectra, photoluminescence (PL) excitation and emission spectra, kinetic decay, and X-ray photoelectron spectra (XPS), respectively. It was found that the Pechini-type sol−gel-derived BPO 4 - x SiO 2 annealed at 1000 °C and BPO 4 - x Al 2 O 3 annealed at 960 °C exhibited bright bluish-white emissions centered at 428 and 413 nm, respectively. The luminescence decay curve analysis indicates that each sample has two kinds of lifetimes (more than 0.4 ms and less than 10 ns) and two types of kinetic decay behaviors, which can be fitted into a double-exponential function and a single-exponential function, respectively. This can be attributed to two kinds of emission centers in samples. The luminescent mechanisms of PSG-derived BPO 4 - x SiO 2 and BPO 4 - x Al 2 O 3 samples were discussed in detail.