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81.
82.
The synergistic influence of lanthanum and cobalt co-doping on room temperature ferromagnetism (RTFM) of TiO2 system is investigated. A series of Ti0.97?xCo0.03LaxO2 nanoparticles were prepared and their structures and properties were systematically studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, UV–vis spectrophotometer, Raman spectra and magnetic measurement techniques, respectively. Detailed experimental characterizations indicate that the as-prepared La and Co co-doped samples exhibit single anatase phase, and all the samples exhibit strong visible photoluminescence associated with oxygen vacancies and a clear ferromagnetic hysteresis loop, both of which were dramatically enhanced with La and Co co-doping, and the maximum saturation magnetization (Ms) reaches 1.38 emu/g at the La content of 6 mol%. It is speculated that oxygen vacancies modulated by ionic La play an important role in the enhanced RTFM, which can be attributed to the bound magnetic polarons (BMPs) formed via ferromagnetic coupling between two neighboring Co2+ ions mediated by oxygen vacancy (F+ center). Our results present an alternative method to obtain high performance RTFM. 相似文献
83.
《Ceramics International》2017,43(3):3166-3170
Cu-doped ZnO was synthesized by hydrothermal method in a pulsed magnetic field. X-ray diffraction reveals the hexagonal wurtzite structure as with pure ZnO. The application of pulsed magnetic field increases the oxygen vacancy content and doping level of Cu2+ analyzed by Raman spectra and X-ray photoelectron spectroscopy. The origin of ferromagnetism is attributed to the oxygen vacancies induced Cu2+ ferromagnetic coupling. 相似文献
84.
Transition Metal Oxides: Electron‐Beam‐Induced Perovskite–Brownmillerite–Perovskite Structural Phase Transitions in Epitaxial La2/3Sr1/3MnO3 Films (Adv. Mater. 18/2014)
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85.
The influence of the stacking fault energy (SFE) on the microstructure, mechanical property and deformation behaviour of stainless steels before and after irradiation was investigated. The mechanical properties, such as strength, ductility, strain hardening and irradiation induced hardening behaviours of 3 alloys with various SFEs are quite different. Such significant variations of mechanical properties must result from the different microstructures, deformation mechanisms and defects accumulation behaviours. Thus, the microstructures, deformation mechanisms and irradiation induced small defect clusters (including their types, natures, densities and size distributions) of 3 alloys are determined in detail by transmission electron microscopy. It indicated that before irradiation, alloy with low SFE has more localised deformation behaviour than alloy with high SFE. After irradiation, in the samples with low SFE, the irradiation induced stacking fault tetrahedral was observed, while in the ones with high SFE, the dominant defects are Frank loops. All the results shown that, SFE has a strong effect on both the deformation mechanism and irradiation induced defect accumulation behaviour of stainless steels. 相似文献
86.
A. A. Galyaev 《Automation and Remote Control》2006,67(6):856-867
The impact of a system of elastically linked material points against an absolutely rigid obstacle is analytically described and limit to an elastic homogeneous rod is studied. 相似文献
87.
The glassy carbon electrode coated with electropolymerized methyl-red film, 1.2 × 10−6 m in thickness, (PMRE) showed high sensitivity towards Hg(II) ions. PMREs were adopted to accumulate and detect Hg(II) ions in a pH 2.56 Britton–Robinson buffer solution. Cyclic voltammogram of the accumulated Hg species on PMREs exhibited an anodic wave at 0.64 V and a cathodic wave at 0.13 V, due to the oxidation of accumulated Hg species on PMREs and the reduction of Hg(II) ions in the solution, respectively. For this heterogeneous adsorption of Hg(II) ions onto PMREs, the maximum surface concentration, adsorption equilibrium, and Gibbs energy change were evaluated to be 5.12 × 10−6 mol m−2, 3.7 × 105 l mol−1, and −30.1 kJ mol−1, respectively. The anodic peak current at 0.64 V was linear with the concentration of Hg(II) ions in the range of 1.1 × 10−10 to 1.1 × 10−7 M with a detection limit of 4.4 × 10−11 M. The proposed method was utilized successfully for the detection of Hg(II) ions in the lake water. 相似文献
88.
Title of program: RANDOM VACANCY MIGRATION Catalog number: ACKO Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland (see application form in this issue) Computer: CDC 6600; Installation: University of Stuttgart Operating system: Scope 3.4 Programming language used: FORTRAN IV High speed storage required: 58 000 words No. of bits in a word: 60 Overlay structure: none No. of magnetic tapes required: none Other peripherals used: card reader, line printer No of cards in combined program and test deck: 718 Card punching code: BCD 相似文献
89.
A mathematical-physical model to describe the current response of p-type SrTiO3 ceramics in the low-temperature regime upon dc voltage step was developed, utilizing the numerical class library DIFFPACK (Numerical Objects, Norway). The current response in the time domain shows the experimentally observed Maxwell-Wagner relaxation (space charge polarization), followed by leakage current, and, eventually, resistance degradation. The relaxation behavior is analyzed by means of the simulation results for the spatial profiles of the electrical potential and the respective point defects. The impact of bias voltage and grain boundaries on the relaxation time is investigated. The simulation results are compared with experimental data. 相似文献
90.
J. Kwon H.F.M. Mohamed W. Kim 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,262(2):255-260
Positron annihilation spectroscopy (PAS) and a computer simulation were used to investigate a defect production in reactor pressure vessel (RPV) steels irradiated by neutrons. The RPV steels were irradiated at 250 °C in a high-flux advanced neutron application reactor. The PAS results showed that mainly single vacancies were created to a great extent as a result of a neutron irradiation. Formation of vacancies in the irradiated materials was also confirmed by a coincidence Doppler broadening measurement. For estimating the concentration of the point defects in the RPV steels, we applied computer simulation methods, including molecular dynamics (MD) simulation and point defect kinetics model calculation. MD simulations of displacement cascades in pure Fe were performed with a 4.7 keV primary knock-on atom to obtain the parameters related to displacement cascades. Then, we employed the point defect kinetics model to calculate the concentration of the point defects. By combining the positron trapping rate from the PAS measurement and the calculated vacancy concentrations, the trapping coefficient for the vacancies in the RPV steels was determined, which was about 0.97 × 1015 s−1. The application of two techniques, PAS and computer simulation, provided complementary information on radiation-induced defect production. 相似文献