Surface morphology and electrocatalytic properties of nickel nanoparticles formed in track pores

© 2016, Pleiades Publishing, Ltd.Structures, each of which is composed of a conducting substrate with a protective dielectric layer containing an array of equal-sized pores formed under the action of high-energy ions and chemical etching, are created. The created pores are electrochemically filled with nickel nanoparticles. With atomic-force microscopy (AFM), it is established that Ni nanoparticles are generated exclusively within ion tracks without film formation on the surface of a silicon-dioxide layer. Histograms illustrating the nanoparticle-diameter distribution are constructed, and areas of the nickel nanoparticles are calculated. The electrochemical and electrocatalytic properties of Ni nanoparticles inherent to ethanol-oxidation reactions are investigated. The catalytic activity per unit area of the nanocatalyst is estimated using voltammograms, AFM data, and histograms characterizing the particle size distribution

Magnetization Reversal of Permalloy Microparticles with the Configuration Anisotropy by Magnetic-Force Microscopy

© 2018, Pleiades Publishing, Ltd. Abstract—Magnetic force microscopy has been used to study the distribution of the magnetization in permalloy microparticles with a configurational anisotropy. The triangular particles with different degrees of concavity of the lateral sides have been studied. An analysis of the results enables us to state that the particles can be in several quasi-homogeneous stable states. It is shown that the particle magnetization reversal can occur both stepwise and also via an intermediate state in the dependence on the particle orientation. It is demonstrated that the quasi-homogeneous magnetization orientation in a particle can be changed by a magnetic-force microscope probe

Atomic-force microscopy of nickel nanoparticles possessing electrocatalytic properties

Surface morphology of highly oriented pyrolytic graphite with electrodeposited nickel nanoparticles was studied by atomic-force microscopy in the presence and absence of ethanol. Voltammetric and atomic-force microscopic data and histograms of particle size distribution were used to evaluate the unit-area catalytic activity of the nanocatalyst in relation to conditions of its preparation. © 2010 Pleiades Publishing, Ltd

Changing the domain structure of CoNi particles under mechanical stress

The work was partly supported by RFBR 17-08-00915

Magnetic force microscopy investigation of the magnetization reversal of permalloy particles at high temperatures

© 2014, Pleiades Publishing, Ltd. The magnetization reversal of an array of permalloy particles formed by scanning probe lithography on the silicon dioxide surface has been investigated in the temperature range from room temperature to 800 K. Using scanning magnetic force microscopy and numerical calculations of the magnetic anisotropy field of a particle at different temperatures, it has been shown that an increase in the temperature leads to a decrease in the external magnetic field required to reverse the magnetization direction of the particle. From the obtained results, it has been concluded that the magnetization reversal of the studied particles is accompanied by the formation of an intermediate state with an inhomogeneous magnetization structure

Atomic force microscopy of cobalt nanoparticles with electro-catalytic properties

A method of controlled potential electrodeposition of the cobalt nanoparticles with sizes from 30 to 400 nm on the surface of highly oriented pyrolytic graphite has been developed. The images of nanoparticles were obtained with an atomic force microscope. A computer program was applied to obtain the size distribution of electrodeposited particles depending on the electrodeposition potential, electrolytic concentration, and deposition time. Using voltammetry it has been established that the cobalt nanoparticles with the diameter of about 50 nm show the maximal catalytic activity during electro-oxidation of ethanol. © Pleiades Publishing, Ltd., 2009

Heat-assisted effects in ferromagnetic nanoparticles

The processes of the magnetization reversal by the external magnetic field of the Py particles have been studied by magnetic force microscopy in the temperature range of 300-650 K. The values of the switching field of the particle magnetization and the switching field distribution for the particles array have been determined. The switching field and the field distribution decrease significantly with increasing temperature. © Published under licence by IOP Publishing Ltd

MFM study of switching magnetization in particles with configurational anisotropy obtained by the microsphere lithography

This work was partially supported by the RFBR grant 18-02-00204

Investigation by MOKE and MFM of the domain structure transformation under mechanical deformations in permalloy microparticles

© Published under licence by IOP Publishing Ltd. In this work, the change in the domain structure of planar permalloy microparticles due to mechanical stress has been studied. For this purpose, an array of particles in a mechanically stressed state was formed on a silicon substrate. In addition, the samples with the array of particles without tension were manufactured. The magnetic structure of the samples was visualized by magnetic force microscopy and hysteresis loops were obtained using the magneto-optical Kerr effect. It was established that the easy magnetization axis collinear to the direction of mechanical stress appears in particles due to mechanical compression. The distribution of magnetization of unstrained particles is mainly determined by the shape anisotropy

Creation of lithographic masks using a scanning probe microscope

© 2015, Pleiades Publishing, Ltd. The experimental results on scanning probe lithography (SPL)—the formation of lithographic masks using scanning probe microscope—are presented. Polymethylmethacrylate (PMMA)-based masks prepared by the SPL method are used to form metal nanoparticles of the specified sizes and shape, as well as the metallic nanowires connecting the contact areas. The analysis of various SPL modes showed that the procedure of point indentation with the switched-on microscope feedback is optimal for the formation of round nanoparticles. When forming the rectangular particles, the procedure of multiple scanning of one region in the contact mode is optimal. The quality of lithographic masks can be substantially increased by the additional use of chemical etching to remove excess PMMA after the mask is formed. The topography and magnetization structure of the formed structures were monitored by atomic force microscopy and magnetic force microscopy