Magnetic Properties of Oxygen-doping Fe-Co-based Nanocrystalline Alloy Films for High Frequency Application

AbstractThe effects of the introduction of oxygen were studied on the Fe62Co32Cr6–O alloy films synthesized by magnetron co-sputtering. The as-deposited films exhibited a high saturation magnetization and a suitable in-plane uniaxial anisotropy field at an optimized condition of an oxygen gas flow ratio of 1.3%. Also, a high real permeability of ∼200 at frequency up to 3.3GHz was obtained from the microwave permeability measurement at the optimized condition above. The combination of high saturation magnetization, adjustable in-plane uniaxial magnetic anisotropy field, and high resistivity makes the Fe62Co32Cr6–O films become a promising candidate for the high-frequency applications

Synthesis of ZnO-ZnCo2O4 hybrid hollow microspheres with excellent lithium storage properties

通讯作者地址: Peng, DLZnO-ZnCo2O4 hybrid hollow microspheres are successfully produced via an annealing process of the pre-fabricated zinc-cobalt citrate hollow microspheres in air. ZnO and ZnCo2O4 have homogeneous distribution within the whole hollow microspheres. The gained hybrid hollow microspheres deliver outstanding lithium storage properties when utilized as the anode material in lithium ion batteries. A high reversible capacity of 1199 mA h g (1) can be retained after 200 cycles. The exceptional electrochemical properties of the hybrid hollow microspheres are ascribed to the synergetic effect between ZnO and ZnCo2O4 nanoparticles, the catalytic effect of Co nanocrystals, the favorable hollow structures together with the nanometer-sized building blocks of hybrid microspheres

Synthesis of ZnO-ZnCo2O4 hybrid hollow microspheres with excellent lithium storage properties

通讯作者地址: Peng, DLZnO-ZnCo2O4 hybrid hollow microspheres are successfully produced via an annealing process of the pre-fabricated zinc-cobalt citrate hollow microspheres in air. ZnO and ZnCo2O4 have homogeneous distribution within the whole hollow microspheres. The gained hybrid hollow microspheres deliver outstanding lithium storage properties when utilized as the anode material in lithium ion batteries. A high reversible capacity of 1199 mA h g (1) can be retained after 200 cycles. The exceptional electrochemical properties of the hybrid hollow microspheres are ascribed to the synergetic effect between ZnO and ZnCo2O4 nanoparticles, the catalytic effect of Co nanocrystals, the favorable hollow structures together with the nanometer-sized building blocks of hybrid microspheres

Magnetic Properties of Oxygen-doping Fe-Co-based Nanocrystalline Alloy Films for High Frequency Application

Conference Name:IUMRS International Conference in Asia (ICA). Conference Address: Taipei, TAIWAN. Time:SEP 19-22, 2011.The effects of the introduction of oxygen were studied on the Fe62Co32Cr6-O alloy films synthesized by magnetron co-sputtering. The as-deposited films exhibited a high saturation magnetization and a suitable in-plane uniaxial anisotropy field at an optimized condition of an oxygen gas flow ratio of 1.3%. Also, a high real permeability of similar to 200 at frequency up to 3.3 GHz was obtained from the microwave permeability measurement at the optimized condition above. The combination of high saturation magnetization, adjustable in-plane uniaxial magnetic anisotropy field, and high resistivity makes the Fe62Co32Cr6-O films become a promising candidate for the high-frequency applications. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of MRS-Taiwa

Preparation of Bimetallic Core-shell Nanoparticles with Magnetically Recyclable and High Catalytic Abilities

Conference Name:IUMRS International Conference in Asia (ICA). Conference Address: Taipei, TAIWAN. Time:SEP 19-22, 2011.In this work, we report the preparation of bimetallic core-shell nanoparticles (NPs) using a simple solution synthetic route. A typical example is the Ag@Ni NPs that are synthesized using oleylamine as solvent and reducing agent. The as-obtained Ag@Ni NPs exhibit a spherical morphology and a highly narrow size distribution. Excellent catalytic properties for the H-2 generation from dehydrogenation of sodium borohydride in aqueous solutions are observed. Similar synthetic strategies have also been developed for the preparation of other bimetallic core-shell NPs, such as Ag@Co and Cu@Ni NPs. These bimetallic core-shell NPs are promising candidates for novel optical and magnetic materials as well as high-performance catalysts. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of MRS-Taiwa

Au-ZnO hybrid nanoflowers, nanomultipods and nanopyramids: one-pot reaction synthesis and photocatalytic properties

Fundamental Research Funds for the Central Universities of China [2011121003]; National Basic Research Program of China [2012CB933103]; National Outstanding Youth Science Foundation of China [50825101]; National Natural Science Foundation of China [51171157, 51171158]The preparation of noble metal-semiconductor hybrid nanocrystals with controlled morphologies has received intensive interest in recent years. In this study, facile one-pot reactions have been developed for the synthesis of Au-ZnO hybrid nanocrystals with different interesting morphologies, including petal-like and urchin-like nanoflowers, nanomultipods and nanopyramids. In the synthesis strategy, oleylamine-containing solution serves as the reaction medium, and the in situ generated Au seeds play an important role in the subsequently induced growth of ZnO nanocrystals. With the aid of several surfactants, hybrid nanocrystals with different morphologies that have considerable influences on their optical and photocatalytic activities are readily achieved. Through high-resolution transmission electron microscopy measurements, an observed common orientation relationship between ZnO and Au is that ZnO nanocrystals prefer to grow with their polar {001} facets on the {111} facets of Au nanocrystals, and well-defined interfaces are evident. Surface plasmon resonance bands of Au with different positions are observed in the UV-vis spectra, and the UV and visible emissions of ZnO are found to be dramatically reduced. Finally, the as-prepared Au-ZnO nanocrystals exhibit excellent photocatalytic activity for the photodegradation of rhodamine B compared with pure ZnO nanocrystals. The Au-ZnO hybrid nanopyramids show the highest catalytic efficiency, which is correlated with the exposed crystal facets, crystallinity and the formation of hybrid nanostructures. The as-prepared Au-ZnO hybrid nanocrystals are expected to find diverse potential applications in the fields such as photocatalysis, solar energy conversion, sensing and biological detection

Disproportionation route to monodispersed copper nanoparticles for the catalytic synthesis of propargylamines

National Basic Research Program of China [2012CB933103]; National Outstanding Youth Science Foundation of China [50825101]; National Natural Science Foundation of China [51171157, 50971108]; Fundamental Research Funds for the Central Universities of China [201112G015]By taking advantage of the coordination between a monovalent Cu+ precursor and trioctylphosphine, monodisperse Cu nanoparticles were synthesized via a disproportionation reaction. A Cu@SiO2 nanocatalyst was formed by supporting Cu nanoparticles onto a silica aerogel, which showed a high surface area (779.53 m(2) g(-1)) and excellent catalytic activity for the synthesis of propargylamines

Engineering oxygen vacancies in hierarchically Li-rich layered oxide porous microspheres for high-rate lithium ion battery cathode

Abstract(#br)Lithium-rich layered oxides always suffer from low initial Coulombic efficiency, poor rate capability and rapid voltage fading. Herein, engineering oxygen vacancies in hierarchically Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 porous microspheres (L@S) is carried out to suppress the formation of irreversible Li 2 O during the initial discharge process and improve the Li + diffusion kinetics and structural stability of the cathode mateiral. As a result, the prepared L@S cathode delivers high initial Coulombic efficiency of 92.3% and large specific capacity of 292.6 mA h g −1 at 0.1 C. More importantly, a large reversible capacity of 222 mA h g −1 with a capacity retention of 95.7% can be obtained after 100 cycles at 10 C. Even cycled at ultrahigh rate of 20 C, the L@S cathode can..

Surface Ni-rich engineering towards highly stable Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cathode materials

Abstract(#br)Li-rich layered oxide cathode materials (LLOs) are regarded as promising next-generation cathode candidate in high-energy-density lithium ion batteries due to their high specific capacity over 250 mA h g −1 . However, LLOs always suffer from a series of severe issues, such as rapid voltage fading, fast capacity decay and bad cycling stability. In this work, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 -Li 1.2 Mn 0.44 Ni 0.32 Co 0.04 O 2 (LLO-111@111/811) hybrid layered-layered cathode is constructed via facilely increasing surface Ni content. Profiting from this special design, the prepared LLO-111@111/811 cathode exhibits a remarkable specific capacity of 249 mA h g −1 with a high capacity retention of 89.3% and a high discharge voltage of 3.57 V with a voltage retention of 83.0% after cycling 350 times at 0.5 C. As a result, the specific energy of LLO-111@111/811 cathode is 887 Wh Kg −1 at 0.5 C and it keeps as high as 658 Wh Kg −1 after 350 cycles. LLO-111@111/811 also exhibits an initial high capacity of 169 mA h g −1 at a high rate of 5 C and maintains a good capacity retention of 90.0% after 200 cycles. This strategy can successfully improve structural stability, suppress capacity decay and restrain voltage fading of LLOs, which is beneficial for their practical application

Thin-Film Lithium Cobalt Oxide for Lithium-Ion Batteries

Lithium cobalt oxide (LCO) cathode has been widely applied in 3C products (computer, communication, and consumer), and LCO films are currently the most promising cathode materials for thin-film lithium batteries (TFBs) due to their high volumetric energy density and favorable durability. Most LCO thin films are fabricated by physical vapor deposition (PVD) techniques, while the influence of preparation on the materials’ properties and electrochemical performance has not been highlighted. In this review, the dominant effects (heating, substrate, power, atmosphere, etc.) on LCO thin films are summarized, and the LCO thin films fabricated by other techniques (spin coating, sol–gel, atomic layer deposition, pulsed laser deposition, etc.) are outlined. Moreover, the modification strategies including bulk doping and surface coating for powder and thin-film LCO electrodes are discussed in detail. This review may pave the way for developing novel, durable, and high-performance LCO thin films by versatile methods for TFB and other energy storage devices