کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1590737 1515463 2007 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Crystal, electronic and luminescence properties of Eu2+-doped Sr2Al2−xSi1+xO7−xNx
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد دانش مواد (عمومی)
پیش نمایش صفحه اول مقاله
Crystal, electronic and luminescence properties of Eu2+-doped Sr2Al2−xSi1+xO7−xNx
چکیده انگلیسی
The crystal and electronic structures, as well as the luminescence properties of Sr2Al2−xSi1+xO7−xNx:Eu2+ are reported. First-principles calculations energetically confirm that the Al and Si atoms are in partial ordering in the 2a and 4e sites in Sr2Al2SiO7. In addition, the band structure calculation shows that Sr2Al2SiO7 has an indirect band gap with an energy gap of about 4.07 eV, which is in good agreement with the experimental data (∼5.3 eV) obtained from the diffuse reflection spectrum. The crystal structure of Sr2Al2SiO7 can be modified by Si-N substitution for Al-O in the lattice with a maximum solubility of about x=0.6. The average bond length of EuSr-(O,N) slightly increases although the lattice parameters decrease with the incorporation of Si-N in Sr2Al2SiO7:Eu2+. Under excitation in the visible spectral region, Sr2Al2−xSi1+xO7−xNx:Eu2+ emits blue to yellow light with a broad emission band in the range of 480-570 nm, varying with both the Eu concentration and the x value. The red shift of the emission band of Eu2+ is associated with an increase in the crystal-field splitting and the covalency, which arise from the incorporation of nitrogen as well as the energy transfer between the Eu ions at high Eu concentrations. Moreover, the Eu ions have a strong effect on both the concentration quenching and the thermal quenching in Sr2Al2−xSi1+xO7−xNx. The temperature dependence of photoluminescence indicates that Sr2Al2−xSi1+xO7−xNx:Eu2+ shows strong thermal quenching due to the dominant nonradiative process at room temperature.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Science and Technology of Advanced Materials - Volume 8, Issues 7–8, October–November 2007, Pages 607-616
نویسندگان
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