AVS2018 Session AC-ThP: Actinides and Rare Earths Poster Session
Thursday, October 25, 2018 6:00 PM in Room Hall B
Thursday Evening
Session Abstract Book
(265KB, May 6, 2020)
Time Period ThP Sessions
| Topic AC Sessions
| Time Periods
| Topics
| AVS2018 Schedule
|
AC-ThP-1 Upconversion Photoluminescence Efficiency Dependence of Yb ions in Gd0.91-xNbO4: Ybx3+, Er0.09
SoungSoo Yi, Seung Gon Lee (Silla University, Republic of Korea) Gd(0.91-x)NbO4 : Er3+0.09, Yb3+x (x= 0.03, 0.06, 0.09, 0.12 and 0.15) phosphors were synthesized by the facile solid state reaction method. Yb3+ concentrations were changed from 0.03 to 0.15 mol for the fixed Er3+concentration at 0.09 mol. The particle size of phosphors was around 180 ~ 350 nm and shape were angular oval observed by scanning electron microscopy. The crystalline structures of the phosphors were investigated by X-ray diffraction. The photoluminescence emission based on the green emissions near 528 and 551 nm and red emissions near 657 and 675 nm were observed and the highest emission intensity occurred for the sample Yb0.15 Er0.09. Also, under the 980 nm excitation, Er3+, Yb3+ co-doped GdNbO4 phosphors appeared the up-conversion emission based on the green emission near 535 nm and 556 nm radiated by 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions and red emission about 657 nm and 675 nm radiated by 4F9/2 → 4I15/2 transition, which assigned to the intra 4f transitions of Er3+ ions. |
|
AC-ThP-2 Luminescence Characteristics of (Gd0.85-xYb0.15)NbO4:Erx3+ Phosphors
SoungSoo Yi, DongGyu Lee (Silla University, Republic of Korea) Gd(0.85-x)NbO4 : Yb3+0.15, Er3+x (x= 0.03, 0.06, 0.09, 0.12 and 0.15) phosphors were synthesized by the solid state reaction method. Er3+ concentrations were changed from 0.03 to 0.15 mol for the fixed Yb3+concentration at 0.15 mol. The crystalline structures of the phosphors were investigated by X-ray diffraction. The particle size of phosphors was around 140 ~ 320 nm and shape were angular oval observed by scanning electron microscopy. The photoluminescence emission based on the blue emission near 471 nm, green emission near 596 nm and red emission near 621 nm were observed and the highest emission intensity occurred for the sample Yb0.15 Er0.09. Also, under the 980 nm excitation, Er3+, Yb3+ co-doped GdNbO4 phosphors appeared the up-conversion emission based on the green emission near 535 nm and 556 nm radiated by 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions and red emission about 657 nm and 675 nm radiated by 4F9/2 → 4I15/2 transition, which assigned to the intra 4f transitions of Er3+ ions. |
|
AC-ThP-3 Exploring the Electronic Structure of Molecular Lanthanide Complexes in the +2 Oxidation State Using Photoelectron Spectroscopy
Daniel Huh, Jared Bruce, John Hemminger, William Evans (University of California, Irvine) Recent advances in rare-earth metal reduction chemistry have led to the isolation of a new series of Ln(II) complexes. For Ln = Y, La, Ce, Nd, Gd, Tb, Dy, Ho, Er, and Lu, reduction of 4fn (C5H4SiMe3)3LnIII complexes generates [(C5H4SiMe3)3LnII]1– products that exhibit unusual 4fn5d1 mixed-principal quantum number electron configurations. X-ray photoelectron spectroscopy (XPS) has been employed to examine and compare these mixed-principal quantum number electronic structures with those of traditional Ln(II) complexes that have 4fn+1 configurations. In this work, X-ray and ultraviolet photoelectron spectroscopy have been used to examine the electronic structure of [K(2.2.2-cryptand)][(C5H4SiMe3)3LnII] (Ln = Eu, Gd, Tb) where Gd(II) and Tb(II) have previously been shown to have non-traditional 4f75d1 and 4f85d1 electronic configurations, respectively, and where Eu(II) has been shown to have a traditional 4f7 electronic configuration. |
|
AC-ThP-4 Effects of Cerium Content on Local Structure in U1-xCexO2 Solid Solution
Hanjie Cao (Shanghai Institute of Applied Physics, Chinese Academy of Science., China); Yuying Huang (Shanghai Institute of Applied Physics, Chinese Academy of Science, China) Uranium–cerium mixed oxides U1-xCexO2 (x=0.05, 0.20, 0.35, 0.50, 0.65, 0.80) were prepared by co-precipitation method. X-ray diffraction data shows that the U1-xCexO2 samples are solid solutions with lattice parameters following Vegard’s law . The local structures of U1-xCexO2 were studied by X-ray absorption fine structure spectroscopy at both U L3 and Ce K edges. To avoid the interference from L2 edge in Ce edge XAFS data, Ce K edge XAFS was used to obtain more accurate local structure of Ce. XAFS data shows that there is local structure disorder in U1-xCexO2 solid solution. The effects of Ce content on the local structure disorder in U1-xCexO2 solid solution were studied. For a cerium content less or equal to about 35%, the disorder increases with the addition of cerium in the U1-xCexO2 solid solution. When the cerium content increases to more than 50% the disorder of the sample decreases rapidly. |
|
AC-ThP-5 Magnetism of the (Nd,R)2Fe14B - H system with R = Er and Tm
Irina Tereshina, Lev Ivanov (M.V. Lomonosov Moscow State University, Russian Federation); Denis Gorbunov (Helmholtz-Zentrum Dresden-Rossendorf, Germany); Mykhaylo Paukov (Charles University, Prague, Czech Republic); Evgeniya Tereshina-Chitrova (Institute of Physics, Academy of Sciences of the Czech Republic); Mathias Doerr (Technische Universität Dresden, Germany); Ladislav Havela (Charles University, Prague, Czech Republic); Alexander V. Andreev (Institute of Physics ASCR, Czech Republic) Since the discovery in 1984, the R2Fe14B (R is a rare earth) compounds received a considerable scientific attention due to their hard magnetic properties [1,2]. Fundamental characteristics of the best permanent magnet Nd2Fe14B are known to be highly sensitive to the atomic substitutions and absorbed light atoms such as hydrogen. In the present work, we studied a combined influence of substitutions of Er and Tm for Nd and hydrogen absorption on the behavior of magnetization in magnetic fields up to 60 T. All studies were conducted on free powder samples at 2 K. It is found that the substitution in the rare earth sublattice decreases the saturation magnetization as a result of ferrimagnetic ordering of magnetic moments of heavy rare earths with respect to the moments of Nd and Fe. However, under sufficiently strong magnetic fields the magnetic moments rotate and in the ideal case, the field-induced ferromagnetic state is observed. This phenomenon is directly connected to the strength of the inter-sublattice exchange interactions (Fe and Nd, Er, Tm sublattices). In the parent materials (Nd0.5Er0.5)2Fe14B and (Nd0.5Tm0.5)2Fe14B in fields up to 60 T no increase of the magnetization was observed. Hydriding of the compounds up to the maximum possible hydrogen content 5.5 at.H/f.u. allows us to observe a forced-ferromagentic state in the (Nd0.5Tm0.5)2Fe14BH5.5 compound. The transition from ferri- to the ferromagnetic state occurs gradually: it begins at the 35 T field and finishes at 55 T. For the compound (Nd0.5Er0.5)2Fe14BH5.5 we also observe a magnetization increase. So that, hydrogenation is found to weaken the intersublattice exchange interaction in these three-sublattice materials. This work is performed with financial support of the grant of Russian Scientific Foundation (project № 18-13-00135). We acknowledge the support of HLD at HZDR (member of the European Magnetic Field Laboratory) and the Materials Growth and Measurement Laboratory (https://mgml.eu [https://mgml.eu/]). [1] J. F. Herbst, Rev. Mod. Phys . 63, 819 (1991). [2] O . Gutfleisch et . al . Advanced Mater . 23 (7), 821 (2011). |