| Popis: |
Yttrium-gadolinium aluminum garnets (YGdAG) doped with Ce 3+ ions have been prepared by co-precipitation method. The luminescent properties of Ce 3+ ions in Gd 3(1− x ) Ce 3 x Al 5 O 12 ( х = 0.01) have been studied upon excitation in the 2–20 eV region. The substitution of Gd 3+ for Y 3+ in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f → 5d excitation bands of Ce 3+ ions, the excitation spectra for the Ce 3+ emission contain bands at 6.67, 7.75, and 9.76 eV. These bands are attributed to the Ce 3+ -bound exciton formation and O 2p → Al 3s, 3p transitions, respectively. Although gadolinium states dominate near the bottom of the conduction band of Gd 3 Al 5 O 12 , contributions from Al tetr and Al oct atoms to the conduction-band density of states are evaluated as quite essential. |
Full Text from ScienceDirect