Improved performance of spherical BaWO4:Tb3+ phosphors for field-emission Displays

Spherical BaW O4: Tb3+ phosphors were prepared by the polyol method and postannealed at 900°C. A variety of properties were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform IR spectra, low-voltage cathodoluminescence, photoluminescence spectra, and lifetime. The as-prepared phosphors were well-crystallized under relatively low synthesis temperature (160°C) and composed of spherical particles with an average size of 100 nm. After postannealing treatment, crystallinity of the phosphors is significantly improved and average particle size is increased to around 220 nm. Under low-voltage (≤4.5 kV) excitation of electron beam, bright green cathodoluminescence was observed, which is attributed to the characteristic emissions from Tb3+ (D35 - FJ7 and D45 - FJ7 transitions). The luminance was significantly improved from 141 to 4866 cd m2 after postannealing, which is mostly attributed to the improvement of crystallinity.