Comparative Study on Photoluminescent Properties of CaGdAlO_4∶Eu^(3+) Phosphors Synthesized with Three Methods

摘要

CaGdAlO4∶Eu3+ powder phosphors were prepared using citrate sol-gel （CSG）, half-dry and half-wet （HDW） and solid state （SS） methods, respectively. X-ray diffraction results confirm the formation of CaGdAlO4∶Eu3+ at 900 ℃ （CSG）, 1200 ℃ （HDW） and 1400 ℃ （SS）, respectively. Field emission scan electron microscopy （FE-SEM） images show that the CaGdAlO4∶Eu3+ powder prepared by the CSG and HDW method has an elliptical shape and that prepared under the SS method has a flaky shape. Upon excitation with 280 nm UV light, all the CaGdAlO4∶Eu 3+ powders show bright red emission on account of the 4f-4f transitions of the Eu 3+ ions. Moreover, the size of the phosphor particles and the emission intensity increase with the increase of calcined temperature. At the same calcination temperature of 1400 ℃, the 5D0→7F2 emission intensity of the sample prepared by HDW method is the highest. Stark components of the 5D0→7FJ emission transitions, both at room temperature and at a low temperature, reveal that the Eu3+ ions occupy only one site with non-centrosymmetry in the crystals.