Abstract: In this work, magnetic force microscopy (MFM) tips coated with a nickel thin-film were prepared and characterized for applications in the measurement of the magnetic write field. Nickel films with various thicknesses in a range of 20 – 80 nm were deposited on silicon substrates and silicon atomic force microscopy (AFM) tips by electron beam evaporation. Film surface morphologies and magnetic properties of the coated nickel films were investigated by using AFM and vibrating sample magnetometry (VSM). The rms roughness increased with the film thickness and was in a range between 0.1 and 0.3 nm. VSM results revealed that the mean coercive field of the nickel films was 20 Oe and there was an increase in the coercivity as the film thickness increased. In addition, the prepared MFM tips were evaluated for the tip response to the dc and ac magnetic field generated from perpendicular write heads. It was found that the MFM tip had the best response to the write field when coated with 60 nm thick nickel film. The coating thickness over 60 nm was inapplicable due to the cantilever bending caused by the film stress.
Abstract: Large-scale fabrication of two-dimensional (2D) nanomaterials by vapor phase depostion enabled the establishment of vertically aligned semiconductor herterojunctions. However, the property modulation of 2D semiconductor heterojunctions remains chanlleging within such thin layers. Herein, we proposed a general strategy towards the surface functionlization of 2D semiconductor heterojunctions simply by two-step atomic layer deposition (ALD) process with following post-annealing. TiO2-WO3 heterojunction was taken as a typical case in this work and its electrochemical properties were significantly improved via the proposed strategy. This strategy may open a new pathway for facile functionalization of 2D nanomaterials for the energy conversion and storage devices.
Abstract: Dielectric elastomer is functional material that can convert electrical energy to mechanical energy. In this paper, a cylindrical dielectric elastomer actuator was designed and fabricated by using fiber stiffening to improve its electromechanical performance. the effects of pre-straining, rate of applied voltage and fiber stiffening on the electromechanical behavior were investigated by the experiments. It was found that the best applied load for pre-straining was 524g based on the electromechanical tests at the applied voltage rate of 10V/s. The maximum actuated strain decreased with an increase in rate of applied voltage. When the fibers were embedded in the dielectric elastomer actuator, the maximum actuated strain was 27.5%, doubled the value of 14% without fiber stiffening at the applied voltage rate of 20V/s.
Abstract: Monolayer WSe2 is flexible, nearly transparent and direct band-gap semiconductor with the potential to be new generation thin film photoelectric conversion materials. The molecule vibration modes of monolayer and bulk WSe2 was analyzed by factor group and the phonons dispersion and vibration frequency was calculated by first-principles based on density functional theory. Furthermore, the comparison between the above calculations and experiment values of Raman shift of monolayer and bulk WSe2 was made to verify the accuracy of theoretical analysis and theoretically explain the differences of monolayer and bulk WSe2 materials in Raman spectra.
Abstract: This research presents effect of sintering temperature T and structural transition process on magnetic and optical properties of as-prepared magnetite Fe2+Cr0.2Fe1.8O4 nanoferrites which synthesized by Co-precipitation method and sintered at different T. Structural phase of crystal lattice was converted from-cubic magnetite-to-maghemite-to-hexagonal hematite with T. Specific surface area S revealed decrease against crystallite size R. Saturation magnetization MS proved dependence on R and porosity P. Strain behavior Ԑ enhanced band gap energy Eg.
Abstract: Magnetoelectric (1−x) BNT−x CFO nanoparticulate thin films with (x = 0, 0.1, 0.2, 0.3) were fabricated by a chemical solution deposition technique. The X-ray diffraction shows that no other secondary phases are observed. Transmission electron microscope (TEM) revels that CFO nanoparticles were well distributed in matrix of BNT. The nanocomposite films exhibit both good magnetic and ferroelectric properties at room temperature (R-T), as well as enhanced magnetoelectric coupling. The composite with x = 0.2, showed the large value of ME voltage coefficient (αE ) ~ 163 mV/cmOe. These ME composites provide a great opportunity as potential lead free systems for ME devices.
Abstract: A compact layer of TiO2, between FTO and mesoporous TiO2 layer of DSSC anode, has the ability to reduce the electron recombination while mesoporous TiO2 layer functions to collect and transport electrons injected by the photoexcited dye. In enhancing the desired functions of compact and mesoporous TiO2, we study the effects of co-doping it with Mg, Eu, and La. MgLa co-doped TiO2 as compact layer has demonstrated higher efficiency due to its increased oxygen vacancies and smaller particle size which results reduced recombination. The combination of pure and co-doped TiO2 nanoparticles to be selected as either compact or mesoporous layer of DSSC anode depends on their respective properties, as demonstrated in this paper.
Abstract: Fluorescence polarization and emission spectra of Rhodamine 6G solution with gold nanoparticles have been studied. It is found that the emission intensities tend to be low when the gold nanoparticles are added into the solution partly due to the energy transfer from the Rhodamine 6G to gold nanoparticles. The fluorescence polarization increases as the concentration ratio of the gold and Rhodamine 6G is more than 124 and decreases as the ratio is about 1115. The enhancement and reduction of fluorescence polarization values are understood as the shortening of the fluorescence lifetime and a temperature effect from the heating of gold nanoparticles, respectively.
Abstract: This work controls the absorption of gold nanoparticles (GNPs) via green synthesis utilizing Sargassum crassifolium extract. The amount of seaweed extract acts as both reducing (from Au+ to Au0) and capping agent. The S. crassifolium extract is mainly composed of biomolecules such as protein and phenolic compounds which are responsible for the synthesis of GNPs. The synthesized GNPs were characterized using UV-Visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy and Transmission Electron Microscopy (TEM). UV-Vis spectra revealed peaks around 505 nm to 544 nm which corresponds to the Surface Plasmon Resonance (SPR) of GNPs. FTIR spectroscopy analysis showed peak at 825 cm-1 and 1144 cm-1 which corresponds to the signature peaks of GNPs. Polydisperse GNPs with varied sizes (between 5 nm to 300 nm) were further confirmed by TEM analysis.