Characteristic and synthesis mechanism of Gd2O2S:Tb phosphors prepared by cold isostatic press pretreatment

Characteristic and synthesis mechanism of Gd2O2S:Tb X-ray phosphors prepared by cold isostatic press (CIP) pretreatment have been investigated by photoluminescence (PL) spectra, luminescence spectra under X-ray excitation (XL), X-ray diffraction (XRD) and scanning electric microscope (SEM). It is shown that the pre-pressed technology reduces the sintering temperature with about 100 °C. It also decreases the particle size, influences the particle size distribution and morphology, and enhances the luminescence efficiencies of PL and XL of Gd2O2S:Tb phosphors greatly. CIP technique also promotes the formation of Gd2O2S by breaking the starting Gd2O3 particles down to smaller particles as well as retarding the sulphur volatilization at low temperature. The nucleation site density in CIP process is higher than that of the normal technology; the cumulative contribution of the possible increase of the nucleation site numbers and the closer packing of the green body, results in finer and more uniform Gd2O2S:Tb particles.