Characteristics of chemical bonding of pentavalent uranium in La-doped UO2

2017 ◽  
Vol 53 (1) ◽  
pp. 115-118 ◽  
Author(s):  
Sergei M. Butorin ◽  
Kristina O. Kvashnina ◽  
Damien Prieur ◽  
Murielle Rivenet ◽  
Philippe M. Martin
Keyword(s):  
Chemical Bonding ◽  
La Doping ◽  
La Doped ◽  
Pentavalent Uranium

HERFD-XAS studies clearly reveal U(v) formation in the cubic environment in UO2 as a result of La doping.

Structural, Magnetic, and Ferroelectric Properties in Ion-Doped BiFeO3 Ceramics

2011 ◽  
Vol 687 ◽  
pp. 391-395
Author(s):  
Shu Xia Zhang ◽  
Yan Wei Ma
Keyword(s):  
Ferroelectric Properties ◽  
Sol Gel ◽  
Structural Phase ◽  
Magnetic Hysteresis ◽  
Synthesis Method ◽  
Secondary Phase ◽  
Rare Earth Ion ◽  
La Doping ◽  
Auto Combustion ◽  
La Doped

Rare-earth ion La is doped at the bismuth site in BiFeO3 to produce Bi0.8La0.2FeO3 polycrystalline ceramics via a sol-gel auto-combustion synthesis method. For comparison, the similar experiments are also carried out for the non-doped BiFeO3 at the same time. It is found that both non-doped and La doped BiFeO3 are composed of nanoscale crystallites (~50 nm). Furthermore, La doping suppresses the formation of the secondary phase and leads to a structural phase transition from a rhombohedral to an orthorhombic or a pseudotetragonal structure. More importantly, the magnetic and ferroelectric properties in La doped ceramics were both enhanced, as evidenced by the typical electric and magnetic hysteresis loops. These property evolutions can be attributed to the elimination of the secondary phase and the structural distortion caused by La doping.

MAGNETIC PROPERTIES OF La-DOPED AND Cu-DOPED ZnO NANOWIRES FABRICATED BY HYDROTHERMAL METHOD

2013 ◽  
Vol 27 (15) ◽  
pp. 1362006 ◽  
Author(s):  
SAN-LIN YOUNG ◽  
HONE-ZERN CHEN ◽  
MING-CHENG KAO ◽  
CHUNG-YUAN KUNG ◽  
CHEN-CHENG LIN ◽  
...  
Keyword(s):  
Growth Rate ◽  
Magnetic Properties ◽  
Room Temperature Ferromagnetism ◽  
Substitution Effect ◽  
Hexagonal Structure ◽  
Zno Nanowires ◽  
Cu Doping ◽  
La Doping ◽  
Doped Zno ◽  
La Doped

La -doped and Cu -doped ZnO nanowires have been prepared to compare the substitution effect on the microstructural and magnetic properties. The XRD patterns of both compositions with single diffraction peak (002) show the same wurtzite hexagonal structure. The growth rate of the ZnO nanowires were enhanced by Cu doping, which were different from the suppression of growth rate by La doping. Room temperature ferromagnetism is observed for all ZnO , Cu -doped ZnO and La -doped ZnO nanowires. The saturation magnetizations are 0.102, 0.232 and 0.04 emu/g for ZnO , Cu -doped ZnO and La -doped ZnO nanowires, respectively. The results showed that the ferromagnetism is restrained by Cu doping, but enhanced by the La doping.

Electrical Characterization and Microstructures of La-Doped Bi4Ti3O12 Thin Films

2011 ◽  
Vol 412 ◽  
pp. 318-321
Author(s):  
X.A. Mei ◽  
Min Chen ◽  
R.F. Liu ◽  
Y.H. Sun ◽  
J. Liu
Keyword(s):  
Thin Films ◽  
Electrical Characterization ◽  
Rf Magnetron Sputtering ◽  
Layered Perovskite ◽  
Random Orientation ◽  
Large Shift ◽  
La Doping ◽  
Si Substrates ◽  
Lower Temperature ◽  
La Doped

La-doped bismuth titanate (Bi4-xLaxTi3O12: BLT) and pure Bi4Ti3O12 (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. La-doping into BIT caused a large shift of the Curie temperature ( TC ) from 675°C to lower temperature and a improvement in dielectric property. The experimental results indicated that La doping into BIT also result in a remarkable improvement in ferroelectric property. The Pr and the Ec values of the BLT film with x=0.75 were 20 μC/cm2 and 82kV/cm, respectively.

Study on Phase Structure and Electrical Properties of La-Doped (K0.5Na0.5)0.94Li0.06NbO3 Ceramics

2011 ◽  
Vol 328-330 ◽  
pp. 1127-1130 ◽  
Author(s):  
Yong Liu ◽  
Rui Qing Chu ◽  
Zhi Jun Xu ◽  
Qian Chen ◽  
Lin Shao ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Phase Structure ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
La Doping ◽  
La Doped ◽  
Lower Loss

Lead-free piezoceramics (K0.5Na0.5)0.94-3xLi0.06LaxNbO3were synthesized by the conventional solid-state reaction process. The effect of La-doping on the phase structure and electrical properties of (K0.5Na0.5)0.94Li0.06NbO3ceramics was investigated. X-ray diffraction analysis showed that the crystal structure of the ceramics changed from coexistence of orthorhombic and tetragonal phases to pseudo-cubic phase with the increase of La-doping level, and the change of phase structure seriously weakened the dielectric, ferroelectric and piezoelectric properties of the ceramics. In addition, it was found that the La-doping improved the density of the ceramics and the ceramics became dense. Meanwhile, the ceramics with La-doping displayed a relative lower loss tangent (tanδ) from room temperature to approximately 350°C.

Effects of low-level La doping and ageing on TlPb-1223 high T c superconductors

Open Physics ◽  
2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Alexander Cigáň ◽  
Gustav Plesch ◽  
Martin Škrátek ◽  
Michal Kopčok ◽  
Ján Maňka ◽  
...  
Keyword(s):  
Meissner Effect ◽  
Zero Magnetic Field ◽  
Nominal Composition ◽  
Induced Voltage ◽  
Oxygen Annealing ◽  
Low Level ◽  
La Doping ◽  
La Doped ◽  
Modest Effect

AbstractBulk samples of the nominal composition of (Tl0.6Pb0.5)(Sr0.8Ba0.2)2Ca2Cu3O8+δ−xLaO1.5 (x = 0–0.1) were prepared by using two-step process and their microstructure, T c values, and magnetization were studied. The samples consist of the Tl-1223 dominant phase with small Tl-1212 admixture, which increases with a rise of La content. Five years ageing and following oxygen annealing at 450°C and subsequently at 750°C have only a modest effect on T c values of the studied samples. Low-level La doping (x = 0:04) leads to an increase of T c values by about 2 K in comparison with undoped samples. Oxygen annealing at 750°C results in an increase in the volume magnetization hysteresis in low applied magnetic fields and rise of critical current density at zero magnetic field and 77 K. This effect is most pronounced for the low La doped sample with x = 0.04. Changes of the induced voltage, U originating in the Meissner effect and of its harmonics in dependence on temperature were measured and used for characterization of the temperature distribution of inter-grain junctions.

Structure and Dielectric Behavior of La-Doped BaTiO3 Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 252-254 ◽  
Author(s):  
Wei Li ◽  
Zhi Jun Xu ◽  
Rui Qing Chu ◽  
Peng Fu
Keyword(s):  
Curie Point ◽  
Sol Gel ◽  
Dielectric Behavior ◽  
Cubic Phase ◽  
Phase Transition Behavior ◽  
Dielectric Characteristics ◽  
La Doping ◽  
Maximum Value ◽  
Lower Temperature ◽  
La Doped

BaTiO3 ceramics doped with 1, 2, 3 and 4 mol% La were prepared by sol-gel method. The effects of La doping on structure and dielectric characteristics of Ba1−xLaxTiO3 were investigated. The results show that: All the powders calcined at 800°C were found to be perovskite structure with cubic phase. Ba1−xLaxTiO3 were sintered at 1300°C, phase transition behavior appeared from tetragonal phase to cubic phase with increasing La-doping level. As the doping concentration increases, the grain growth of the Ba1−xLaxTiO3 ceramics was controlled efficiently and Curie point shifted to lower temperature. The grain size decreased from 20μm with 0 mol% La doped to 0.5μm with 4 mol% La doped. The Curie point shift rate was 22 °C/ mol% with increasing La content. The dielectric constant of La doped Ba1−xLaxTiO3 ceramics increased with increasing La content and a maximum value of 8900 was attained with 4 mol% La doped.

Fabrication and Photoelectric Properties of La-Doped ZnO Nanofibers via Electrospinning

2015 ◽  
Vol 733 ◽  
pp. 257-260 ◽  
Author(s):  
Yi Chen Liu ◽  
Xu Yan ◽  
Wen Peng Han ◽  
Hong Di Zhang ◽  
Yun Ze Long
Keyword(s):  
Crystal Structure ◽  
Light Illumination ◽  
X Ray Diffraction ◽  
X Ray ◽  
La Doping ◽  
Photoelectric Properties ◽  
Zno Nanofibers ◽  
Doped Zno ◽  
La Doped ◽  
Scanning Electron

La-doped ZnO nanofibers were fabricated via electrospinning and calcination at 800°C. The surface morphology and crystal structure of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photoelectric properties of La-doped ZnO nanofibers were also investigated. It was found that the photoelectric current increased obviously under light illumination (308 nm and 365 nm). However, the photocurrent reduced with increasing La-doping level, which may be ascribed to the increased defects inducing by La-doping.

Effect of La Doping on the Structure and Lithium Storage Performance of V2O5

2019 ◽  
Vol 19 (11) ◽  
pp. 7421-7426 ◽  
Author(s):  
Shangwang Le ◽  
Shengshan Wen ◽  
Zhengguang Zou ◽  
Yanwei Li
Keyword(s):  
Sol Gel ◽  
Rate Capability ◽  
Reversible Capacity ◽  
High Rate ◽  
Electrode Polarization ◽  
Lithium Storage ◽  
Transfer Resistance ◽  
La Doping ◽  
Storage Performance ◽  
La Doped

La-doped vanadium pentoxide (V2O5) was prepared by sol–gel method and subsequent heat treatment in air at 400 °C. The influence of La-doping on the crystalline structure, surface morphology, and lithium storage performance of V2O5 were investigated by XRD, SEM, CV, EIS, and discharge–charge tests. The results demonstrated that La doping did not change the phase structure of orthorhombic V2O5, but significantly refined the crystal grain of V2O5; La doping obviously improved the cycling stability and rate capability of V2O5 due to the decreased electrode polarization, smaller electron-transfer resistance, and enhanced lithium diffusivity. For example, the La-doped V2O5 delivered a reversible capacity of 131 mAh/g after 50 cycles at a current density of 200 mA/g, while the pure V2O5 showed a reversible capacity of only 63 mAh/g under the same condition. At the high rate of 500 mA/g, the La-doped V2O5 still displayed a reversible capacity of 106 mAh/g, which is two times higher than that (45 mAh/g) of pure V2O5 sample.

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