Structural, EPR, optical and Raman studies of Nd₂O₃:Cu²⁺ nanophosphors

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• 作者：B. Umesh^a ; ^b ; B. Eraiah^b ; ^{eraiah@rediffmail.com} ; H. Nagabhushana^c ; ^{bhushanvlc@gmail.com} ; S.C. Sharma^c ; B.M. Nagabhushana^d ; C. Shivakumara^e ; J.L. Rao^f ; R.P.S. Chakradhar^g
• 关键词：Nanoparticles ; PXRD ; SEM ; TEM ; EPR ; Raman ; Optical properties
• 刊名：Spectrochimica Acta Part A ; Molecular and Biomolecular Spectroscopy
• 出版年：2012
• 期刊代码：99_13861425
• 类别：ch
• 出版时间：August, 2012
• 卷：94
• 期：Complete
• 页码：365-371
• 文件大小：720 K

摘要

Nanocrystalline Nd₂O₃:Cu²⁺ (2 mol%) phosphors have been prepared by a low temperature solution combustion technique. Powder X-ray diffraction (PXRD) results confirm that hexagonal A-type Nd₂O₃ (900 掳C, 3 h) and the lattice parameters have been evaluated by Rietveld refinement. Surface morphology of as-formed and Cu²⁺ doped Nd₂O₃ phosphors show that the particles are irregular in shape and porous in nature. TEM results also confirm the nature and size of the particles. The EPR spectrum exhibits two resonance signals with effective g values at g_莯莯 鈮?/strong> 2.12 and g_{鈯?/sub> 鈮?/strong> 2.04. The g values indicate that the site symmetry of Cu²⁺ ions is octahedral symmetry with elongated tetragonal distortion. Raman studies show major peaks, which are assigned, to Fg and combination of Ag + Eg modes. It is observed that the Raman peaks and intensity have been reduced in Cu²⁺ doped samples. UV-Visible absorption spectra exhibit a strong and broad absorption band at 鈭?40 nm. Further, the absorption peak shifts to 鈭?4 nm in Cu²⁺ doped samples. The optical band gap is estimated to be 5.28 eV for Cu doped Nd2O3 nanoparticles which are higher than the bulk Nd2O3 (4.7 eV). This can be attributed to the quantum confinement effect of the nanoparticles.}