[Preparation and luminescent properties of CaMoO4:Tb3+]

The precursor of the sample CaMoO4:Tb3+ was prepared by the coprecipitation method. TG-DTA spectra show that there is, at 850 degrees C, an energy absorption peak, suggesting that the sample reaches the activation spot of its response. The XRD pattern of the roasted sample shows that CaMoO4:Tb3+, in the single phase, is a representative scheelite structure of CaMoO4, but the peaks shift toward right, implying that tiny crystal defect in the crystal is produced. The defect is likely to be formed by the formation of the holes as two Tb3+ replace three Ca2+ in a cell. The excitation and emission spectra of the sample were investigated and revealed that the defect structure of the sample is in favor of the energy transfer of the characteristic peak (488 nm) of the MoO4(2-) effectively to Tb3+, and makes the 4f electrons of the Tb3+ transit, especially the (7)F6-->(5)D4 electronic transition (488 nm) of the Tb3+, to be greatly strengthened. As a result, the emission spectra with lamdaex=488 nm show that the emission intensity of the spontaneously activated fluorescence MoO4(2-) is greatly weakened, while the green light luminescence intensity of the (5)D4-->(7)F5 transition (544 nm) of the Tb3+ is greatly enhanced. This suggests that the sample CaMoO4:Tb3+ will become the luminescence material with potentially great application value.