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Iron oxide (Fe3O4) nanoparticles are synthesized using the chemical co-precipitation method. Changing factors such as surfactant, pH, and molar ratio of ferrous to ferric ions effects the size and magnetic properties of the nanoparticles significantly. The synthesized nanoparticles are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). The nanoparticles have inverse spinel structure. Superparamagnetic behavior is detectable for all samples. The variations of magnetic properties for different sized Fe3O4 nanoparticles can be explained with surface effects and finite size effects. [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]

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1134/S1063776122320012 [ABSTRACT FROM AUTHOR]

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1134/S0022476622080194 [ABSTRACT FROM AUTHOR]

A correction notice for the article "Laser wavelength and dose effects on Al nanoparticles structural formation in deionized water" is presented, which was published in the March 11, 2020 issue of the periodical.

A correction notice for the article "Mn ferrite nanoparticle generation in distilled water using Nd:yttrium aluminum garnet laser" is presented, which was published in the March 11, 2020 issue of the periodical.