Electron paramagnetic resonance and photoluminescence properties of α-Al2O3:Cr3+ phosphors
Electron paramagnetic resonance and photoluminescence properties of α-Al2O3:Cr3+ phosphors
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DOI：
10.1007/s00340-012-4993-x
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发表时间：
2012-04
期刊：
影响因子：
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通讯作者：
Vijay Singh;R. Chakradhar;J. Rao;Katharina Al-Shamery;Markus Haase;Y. Jho
中科院分区：
文献类型：
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作者：
Vijay Singh;R. Chakradhar;J. Rao;Katharina Al-Shamery;Markus Haase;Y. Jho
以金属硝酸盐和尿素为原料，采用简易燃烧法制备了Cr ~（3+）激活的α-Al_2 O_3红色荧光粉，其起燃温度为500 °C。采用X射线衍射、扫描电镜和傅里叶变换红外光谱等技术对合成粉体进行了表征。X射线衍射分析表明，燃烧反应直接导致荧光粉以六方相α-Al 2 O3晶化。EPR谱表现出强的共振信号，其有效g值为沿着为3.33，以及一些弱的共振信号，其有效g值为13.7、2.34、1.95、1.49和1.26。计算了自旋浓度（N）和顺磁磁化率（χ）。激发光谱由415 nm和555 nm两个宽的强带组成，分别归属于4A 2g（F）→ 4 T1 g（F）和4A 2g（F）→ 4 T2 g（F）跃迁。691 nm附近的强荧光峰归属于Cr ~（3+）离子的2 Eg → 4A 2g跃迁。通过EPR和光学数据的关联，计算并讨论了晶体场分裂参数（Dq）和Racah电子间排斥参数（B）。EPR和光学研究表明，Cr 3+离子以八面体配位方式占据Al 3+位置。
The red emitting Cr3+activatedα-Al2O3powder phosphor has been prepared by easy combustion reactions from mixed metal nitrate reactants and urea with ignition temperatures of 500 °C. The as-synthesized powder was characterized by X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared techniques. The X-ray diffraction pattern reveals that the phosphor crystallized in the hexagonalα-Al2O3phase directly from the combustion reaction. The EPR spectrum exhibits an intense resonance signal with effectivegvalue atg=3.33 along with a few weak resonance signals with effectivegvalues atg=13.7, 2.34, 1.95, 1.49, and 1.26. The spin concentration (N) and its paramagnetic susceptibility (χ) have been evaluated. The excitation spectrum consists of two broad intense bands at 415 nm and 555 nm and are assigned to4A2g(F)→4T1g(F) and4A2g(F)→4T2g(F) transitions, respectively. The intense fluorescence peak around 691 nm is attributed to2Eg→4A2gtransition of Cr3+ion. By correlating EPR and optical data, the crystal field splitting parameter (Dq), Racah inter-electronic repulsion parameter (B) have been evaluated and discussed. The EPR and optical studies reveal that Cr3+ions are occupying in Al3+sites in octahedral coordination.