Lai Sen Wang

Effects of Ce doping on the properties of ZnO thin films prepared by DC reactive magnetron sputtering

The ZnO and ZnO:Ce thin films were prepared by DC reactive magnetron sputtering. The structure, surface morphology, optical and photoluminescence properties of ZnO:Ce thin films were investigated. The XRD results indicated that all the samples exhibited a hexagonal wurtzite structure. The surface morphology of the films was sensitive to the Ce concentration. All the films had a higher average transmittance (more than 85%) in the visible region and a strong absorption near the band-edge of ZnO. The photoluminescence properties of the Ce-doped ZnO thin films were also studied. Blue emissions were observed from the ZnO:Ce thin films. Our results indicated that the photoluminescence properties of ZnO thin films doped with low Ce concentration were related to the intrinsic transition of Ce3+ ions. However, when the Ce concentration increased, Zni also played an important role.

Structure and optical properties of SnS nanowire arrays prepared with two-step method

Abstract. Single crystalline SnS nanowire arrays have been synthesized by sulfurating the Sn nanowire arrays which were prepared with the electrochemical deposition. The obtained SnS nanowire arrays are charactered with the XRD, SEM, TEM and the UV/Visible/NIR spectrophotometer. And the results indicate that the nanowires with an average diameter of 50 nm and a length of several tens micrometers, which same with the as prepared Sn nanowires. There are two absorption peaks indicate with the direct and indirect bandgaps about the orthorhombic SnS nanowire arrays.

Soft magnetic property of [Fe80Ni20-O/ZnO](n) multilayer thin films for high-frequency application

A series of [Fe80Ni20-O/ZnO]n multilayer thin films with different ZnO separate layer thicknesses (t, from 0 to 3 nm) and fixed Fe80Ni20-O layer thickness (about 5 nm) have been fabricated on (100)-oriented silicon wafers and glass substrates by reactive magnetron sputtering. Microstructure analysis and static magnetic measurement results indicate that the magnetic properties of the films can be adjusted by the variation of ZnO monolayers thickness. All films reveal an evident in-plane uniaxial magnetic anisotropy (IPUMA). The values of in-plane uniaxial magnetic anisotropy fields (Hk) and resistivity (ρ) can be changed from 8 to 57 Oe and 62 to 168 μΩ•cm respectively with the t increasing. While the values of hard axis coercivity (Hch) and easy axis coercivity (Hce) reveal minimums of 1.5 and 3 Oe respectively at t = 1 nm.

Integrated Solenoid Inductor with [FeCoSiN/SiN x ] 18 Multilayer Magnetic Film for GHz Applications

In this work, we explored the solenoid inductor integrated [FeCoSiN/SiNx]18 multilayer magnetic film as magnetic core used in GHz range. The multilayer magnetic film was employed due to its high resistivity and excellent soft magnetic properties even in GHz range. It was found that this magnetic core material can dramatically increase the performance of the solenoid inductor, which presenting a 10-fold improvement in the inductance and a 23-fold enhancement in the quality factor at 1.67 GHz in comparison to those of the air core solenoid inductor. Besides, an inductance density of 27 nH/mm2 and a self-resonant frequency of 3 GHz were also achieved. The results indicated that the solenoid inductor with multilayer magnetic core showed good high frequency characteristics.

Soft Magnetic Properties of [Fe80Ni20-O/NiZn-Ferrite]n Multilayer Thin Films for High Frequency Application

In this research, a series of [Fe80Ni20-O/NiZn-ferritn multilayer thin films with different insulation layer thickness were prepared by magnetron sputtering at room temperature. The high frequency soft magnetic properties of [Fe80Ni20-O/NiZn-ferritn multilayer thin films were investigated. It was found that the in-plane magnetic anisotropy field (Hk) and saturation magnetizations (4πMs) can be adjusted by changing the insulation layer thickness, and the optimal Hk and 4πMs can be obtained as the insulation layer thickness of 2.5 nm. The adjustment of insulation layer thickness is essential to obtain low coercivity (Hc) and high permeability (μ) of the multilayer thin films. The measured resistivity (ρ) of [Fe80Ni20-O/NiZn-ferritn multilayer thin films was increased from 211 to 448 μΩcm with increasing the insulation layer thickness.

The improvement of Pd nanoclusters electro-catalytic properties for FAO by the addition of Co element

Near-monodisperse Pd and PdCo nanoclusters were synthesized by physical vapor deposition using a plasma-gas-condensation cluster deposition system and tested for catalyzing formic acid oxidation. Under the condition of high vacuum and inert gas, NCs with clean surface and uniform size were obtained. The cyclic voltammetry tests revealed that the electrochemical surface area was increased from 49.7 m2 g-1 to 51.7 m2 g-1 and the peak current density of catalyzing FAO was raised from 0.115 mA cm-2 to 0.125 mA cm-2 when about 12wt. % Co element was added. Additionally, the tolerance to CO poisoning of Pd could also be improved by the addition of Co. The result indicated that this method offered a chemical-free way to prepare clean and efficient Pd-based nanoscale catalytics and encouraged deeper exploration for electrochemichal catalytic reactions.

Preparation of gold-nickel phosphide core-shell nanoparticles via a facile solution method

Core-shell nanomaterials have been one of the most attracting research targets in the field of nanoscience and technology due to the multiple functionalities contributed from different components. In this paper, we report a facile solution synthetic method for the preparation of gold-nickel phosphide core-shell nanoparticles that have a near-spherical morphology and a size of ~20 nm. Transmission electron microscopy along with energy dispersive X-ray spectroscopy analyses reveals a core-shell structure consisting of gold core and nickel phosphide shell. The optical absorption data show that the surface plasmon resonance band of gold in the visible range is greatly decreased by coating nickel phosphide shell. The result of magnetic measurement reveals that the as-prepared core-shell nanoparticles basically exhibit paramagnetic characteristics. The obtained gold-nickel phosphide core-shell nanoparticles can be applied in application fields such as catalysis.

The structure and magnetic properties of NiZn-ferrite films deposited by magnetron sputtering at room temperature

NiZn-ferrite thin films were deposited onto silicon and glass substrates by radio frequency magnetron sputtering at room temperature. The effects of the relative oxygen flow ratio on the structure and magnetic properties of the thin films were investigated. The study results reveal that the films deposited under higher relative oxygen flow ratio show a better crystallinity. Static magnetic measurement results indicated that the saturation magnetization of the films was greatly affected by the crystallinity, grain dimension, and cation distribution in the NiZn-ferrite films. The NiZn-ferrite thin films with a maximum saturation magnetization of 151 emucm-3, which is about 40% of the bulk NiZn ferrite, was obtained under relative oxygen flow ratio of 60%.