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Eu^(3+)가 첨가된 Gd₂O₃나노튜브의 제조 및 광학적 특성
배동현,장기완,이호섭,이성수,정중현 한국물리학회 2011 새물리 Vol.61 No.7
습식법을 이용하여 전구체 Gd₂O₃나노튜브를 제조한 후, 공기중에서의 열처리를 통하여 Eu^(3+)가 첨가된 Gd₂O₃ 나노튜브를제조하였다. 제조된 시료의 구조 및 형상은 XRD, 라만분광 및 FE-SEM을이용하여 분석하였으며, 광활성제로 첨가된 Eu^(3+)의 광학적 특성은여기 및 발광스펙트럼 등의 측정을 통하여 분석하였다. 라만스펙트럼의분석을 통하여 기존에 보고되지 않은 새로운 피크가 존재한다는 사실을확인하였으며, 전하이동밴드에 의한 여기효율은 Gd₂O₃ 나노튜브에첨가된 Eu^(3+)의 농도가 7%일 때에 가장 좋았다. 254 nm의여기파장으로 시료를 여기하여 Eu^(3+)에 기인한 발광스펙트럼을측정한 결과, 전형적인 Eu^(3+)에 기인한 발광특성를 보여주고 있으며,모든 천이들 가운데에 ^5(D_0)-^7(F_2)천이에 해당하는 613 nm 에서발광세기가 가장 강하였다. 또한, Gd₂O₃의 용융온도가 2,330℃ 매우 높은데도 불구하고, 열처리 온도가 1,100℃이상에서는 나노튜브가 용융되기 시작한다는 사실도 확인하였다. Eu^(3+) doped Gd₂O₃nanotubes were prepared by employing a simple wet-chemical route through heat treatment in air by using Gd(OH)3 as the precursor. Their structural and morphological features were analyzed by using X-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscopy (FE-SEM). The photoluminescent properties of Eu^(3+) doped Gd₂O₃ nanotubes were studied by measuring their excitation and emission spectra. New Raman peaks, not previously reported were found at 250 cm^(-1) through an analysis of Raman spectra. We also noticed a strong charge transfer band in the excitation spectrum of Eu^(3+) doped Gd₂O₃ nanotubes, and it quenched at 7 mol% of Eu^(3+). Using 254 nm as the excitation wavelength, we recorded the emission spectr of Eu^(3+) doped Gd₂O₃ nanotubes, and it exhibited all the characteristic transitions of the Eu^(3+) dopant ion, and among all, the ^5(D_0)-^7(F_2) transition at 614 nm was most intense. Even though bulk Gd₂O₃ has a high melting temperature of 2,330℃, the studied nanotube samples began to melt at 1,100℃.
鄭重鉉 연세대학교 대학원 1967 延世論叢 Vol.5 No.1
The effects of zone refining of metallic bismuth on number of passes, zone width and yield of pure bismuth were studied. The optimum clone speed was obtained to be about 1.0mm/min. By the spectroscopic analysis, obtained distribution coefficients of the major inpucities, Cu, Ag, Pb and Te were 0.5, 0.3, 0.4 and 0.7 respectively. The distribution coefficient k of Ag in bismuth crystal grown by the normal freezing method was determined using a radioactive tracer Ag111, and the value obtained is 0.38.
Luminescence Properties of Mn2+-Doped Zn2SiO4 Thin Films Grown by Using Pulsed Laser Deposition
정중현,양현경,정종원,문병기,최병춘,이성수,김정환 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3
Zn2SiO4:Mn2+ luminescent thin films were grown on Al2O3 (0001) substrates by using a pulsed laser deposition technique at substrate temperature of 600 ℃ under various oxygen pressures of 100, 200, 250, 300, 350 and 400 mTorr. The mechanism for the enhanced efficiency of the green emission from the Zn2SiO4:Mn2+ thin lms was investigated for various oxygen pressures. The crystallization, the surface morphology and the luminescent properties of Zn2SiO4:Mn2+ thin films are very dependent on the variation in the oxygen pressure. The enhanced luminescence for Zn2SiO4:Mn2+ thin films at an oxygen pressure of 400 mTorr may result not only from the improved crystallinity but also from reduced internal reflections caused by rougher surfaces. Also, the luminescent intensity and the surface roughness of the lms exhibited similar behaviors as functions of the oxygen pressure.
광음향효과를 이용한 FMR 및 EPR 측정에 관한 연구
정중현,도시홍,김성부 釜山水産大學校 1983 釜山水産大學 硏究報告 Vol.23 No.1
A photoacoustic detection technique of ferromagnetic resonance (FMR) and electron paramagnetic resonance (EPR) is reported. The theory of the photoacoustic effect with solids is derived for a simple cylindrical photoacoustic cell. Several experiments were performed on the samples to verify the validity of the theory. The used samples are the Fe foil and MnSO₄·4H₂O crystals and the applied electromagnetic wave is the modulated 9.1 GHz microwave. The value of the dc magnetic field required for FMR is found to be 0.5 K gauss and the calculated spectroscopic splitting factor g is 1.96. The value of the dc magnetic field at peak position of the EPR absorption is 3.4±9.1 K gauss which corresponds to the g value of 1.91±0.05 and the absorption curve has approximate line halfwidth of 580 gauss.
鄭重鉉,尹玄佑,姜鉉植,太正學 연세대학교 대학원 1976 延世論叢 Vol.13 No.2
The nature of the green euminescence center in N-ion implanted ZnSe has been investigated. The N-ion were implanted with energy of 60 keV at dose of 1015 ions/cm2. The photoluminescence excited by UV lamp always exhibits edge emission, intense green and weak red at 77˚k, peaked at 4630Å (2.68 eV), 5300Å (2.34 eV) and 6300Å (1.98 eV), respectively, The edge emission and green band completely quenched out at above 210˚K, but the red band did not. By observing the temperature dependence of the peak energy shift and the variation of the half-width of the photoluminescence spectra the green center can be assumed to be the localized one and the transition type classified into Scho‥n-Klasen's model. The activation energy estimated from the above measurement was 0.11 eV.
정중현,김명욱,박승철,김근묵,엄영호,노삼규 연세대학교 자연과학연구소 1982 學術論文集 Vol.9 No.-
처음으로 반절연성 InP:Fe를 SSD법으로 생장시키었다. Fe를 각각 0.5와 1.0 wt-% 첨가한 결정의 비저항은 실온에서 각각 3.1×10^7와 1.5×10^7Ω·cm이었으며, 저항의 온도 위존성에서 얻은 Fe의 에너지 준위는 전도대의 바닥 아래로 0.66 eV이었다. For the first time we obtained the semi-insulating InP:Fe crystals grown by SSD method. Their resistivities were 3.1×10^7 and 1.5×10^7Ω·cm in the Fe-doped crystals with contents of 0.5 and 1.0 wt-%, respectively. Temperature dependence of the crystal revealed the energy level of Fe as 0.66 eV from the bottom of the conduction band.