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In many modern sciences, electron transfer is required, such as electron microscopes, microwaves, and screens. There have been numerous reports of the formation of microstructures on silicon surfaces using lasers in halogen-containing media and their optical, electrical and other physical properties. A silicon microstructured field emitter is modeled with Fowler-Nortium field diffusion theory, and the breakdown currents are consistent. Breakdown voltage, field gain coefficient, current and current density, and emitter region (in case of breakdown) are considered in the simulation. Comparison between simulation and experimental results shows that the microstructure has field emitter properties and can be used as a new field emitter. [ABSTRACT FROM AUTHOR]

Fe3O4 magnetic nanoparticles have been synthesized successfully in chemical co-precipitation method and coated with oleic and citric acids, separately. The crystalline sizes are determined by the Debye-Scherer equation with X-ray powder diffraction data. As a result, the mean crystalline size and lattice constant of Fe3O4 nanoparticles respectively increases from ~11 to ~13.8 nm and ~8.352 to ~8.3696 Å when the oleic acid surfactant is replaced by citric acid. The superparamagnetic behavior of the nanoparticles has been documented by the hysteresis loop measured at 300 K. The Fe3O4 nanoparticles show the magnetic saturation values of ~8.136 and ~17.7 emu g–1 for oleic and citric acid coated, respectively. IR spectroscopy has revealed that oleic acid is chemisorbed via a carboxyl group onto the surface of the iron oxide nanoparticle and is coordinated symmetrically to the oxide atoms. Furthermore, there is a ligand exchange between –OH groups and –COO groups on the Fe3O4 nanoparticle surfaces. [ABSTRACT FROM AUTHOR]

This work reports a study of the structure and magnetic behavior of NiFe2O4 ferromagnetic oxide nanoparticles synthesized by the combustion method. The structural and magnetic properties of nanoparticles after mechanical milling are investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, transmission electron microscope. Their structural properties and magnetic behavior are characterized by a vibrating sample magnetometer (VSM). The non-milled sample presents a coercivity of 89 Oe, a saturation magnetization of 69 emu/g, and a remanence of 13 emu/g. After milling, the sample attains the coercivity, the saturation magnetization, and the remanence of 160.7 Oe, 56 emu/g, and 12.8 emu/g respectively. The porosity estimated from the X-ray density and bulk density is about 35%. The XRD analysis by Stokes-Wilson, Williamson-Hall, and dislocation density equations are used to estimate strain and the dislocation density induced by mechanical milling in the sample. [ABSTRACT FROM AUTHOR]

The nano core-shell can be generated in a proper liquid medium under controlled laser ablation condition. In this work, the formation of core-shell structure by laser ablation of two different targets was modeled based on the Smoluchowski approach. In this model, the movement and aggregation of the ablated fragments ejected from the targets were investigated based on Brownian motion, hydrodynamics considerations and coulomb's interactions. The nano core-shell could be generated in the water under controlled exposure conditions using Q-SW Nd:YAG laser shots at 1064 nm. This work addresses a simple numerical modeling of the formation of core-shell nanoparticles in water by laser ablation. The late stage of nanoparticle formation by collisional aggregation was considered avoiding hydrodynamic calculations. Each collision is assumed to be effective in aggregate formation. The rate constants are simply expressed through the diffusion coefficient depending on the temperature and viscosity of the liquid and the aggregation time was estimated. Moreover, Smoluchowski approach was used to describe the step between laser ablation and nano core-shell creation. This proves to be a suitable method for modeling of nanoparticle formation in liquid by laser ablation. The model could be applied to both the nanoparticle and the core-shell formation; however the latter is emphasized here. At first, the gold target was irradiated in water to generate nano particles. Then, the silver target was immersed into water-gold suspension. It was irradiated by multiple laser shots subsequently. The nano core-shells (Ag-Au) are created in the water having 30-50 nm size. The formation of core-shell using laser ablation of metallic targets was modeled based on the Smoluchowski approach. The movement and aggregation of the ablated fragments ejected from the targets were investigated based on Brownian motion, hydrodynamics considerations and coulomb's interactions. For investigation of validation of the model, the results obtained by the model for the nano core - shell (Ag-Au) generation were comprised with reported experimental results. Modeling was based on the irradiation on gold target in water to generate Au nano particles. Then, the silver target was immersed into water-gold suspension. It was irradiated by multiple laser shots subsequently in the liquid medium. The predicted sizes of the nano core-shells (Ag-Au) by the model were 30-50 nm which were in good agreement with experimental reported results. [ABSTRACT FROM AUTHOR]

In this work, Al nanoparticles were generated using Pulsed Nd : YAG laser (1064 nm) ablation in water confined plasma. Productions were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and selected area electron diffraction (SAED). Laser ablation of the Al target in deionized water leads to fabrication core-shell type structure due to partial oxidation in the water medium. The Nano sized core-shells are spherical in shape and have mean size ~ 16 nm. NPs were in the crystalline form as bulk Al. Obviously, the chemical composition of the Nano sized core-shells surface must be Al2O3 because of water medium. [ABSTRACT FROM AUTHOR]