28 research outputs found
SYNTHESIS AND LUMINESCENT INVESTIGATION ON THE CALCIUM SILICATE CA3 SI 2 O7 , ACTIVATED WITH EU2+ IONS
The thermodynamic analysis of possible chemical processes occurring in the system
CaO:SiO2=3:2 was carried out. Optimized conditions for the preparation Ca3(1-х)Eu3xSi2O7 firm solutions have been determined. It was shown that the effective luminescence of Eu2+ions in Ca3Si2O7 with a maximum at 625 nm creates pre-conditions for the use of this material as a phosphor for white light-emitting diodes
Position of the optical absorption edge of alkaline earth borates
Based on the results of luminescent measurements on MBO (M = Ca, Sr), CaBOCl, SrBO, SrAl_2_7_2_4_3_3_2_2_4_6_{10}_4_7^{2+}$ states from the top of the valence band; (b) a more efficient stabilization of the O 2p states by B–O covalent bonding with increasing condensation degree of the borate anion
Luminescence properties and electronic structure of -doped gadolinium aluminum garnet
Yttrium-gadolinium aluminum garnets (YGdAG) doped with Ce3+ ions have been prepared by co-precipitation method. The luminescent properties of Ce3+ ions in Gd3(1−x)Ce3xAl5O12 (х = 0.01) have been studied upon excitation in the 2–20 eV region. The substitution of Gd3+ for Y3+ 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 Ce3+ ions, the excitation spectra for the Ce3+ emission contain bands at 6.67, 7.75, and 9.76 eV. These bands are attributed to the Ce3+-bound exciton formation and O 2p → Al 3s, 3p transitions, respectively. Although gadolinium states dominate near the bottom of the conduction band of Gd3Al5O12, contributions from Altetr and Aloct atoms to the conduction-band density of states are evaluated as quite essential