Magnesium orthovanadate Mg3V2O8 provides an excellent model for studying the transport of magnesium cations in a three-dimensional matrix with two types of Mg(1)O-6 and Mg(2)O-6 octahedra connected by edges and chains of VO4 tetrahedra isolated from each other. In the present paper, the magnesium cations have been found to be the ionic charge carriers in this system using the Tubandt method. The electrical conductivity (sigma) has been studied by the impedance spectroscopy in the range 770-1270 K. The activation energy of sigma (E-sigma) has been demonstrated to be 1.25 eV in the range 923-1023 K. For the first time, the V-51 NMR spectra have been obtained and analysed in the range 295-900 K. The activation energy (E-NMR) for the diffusive jumps of Mg2+ cations has been identified to be 1.03 eV by analyzing the temperature dependence of the V-51 spin-lattice relaxation. The smaller E-NMR value is due to the rapid movement of magnesium along the chains of Mg(2)O-6 octahedra. Large E-sigma value and low ionic conductivity indicate that the limiting step in Mg3V2O8 is the cation hopping between the chains of Mg(2)O-6 octahedra through the intermediate Mg(1) positions.

A series of nanoparticles of the bimetallic core and carbon shell type FexCo1-x@C (x = 0.4 - 0.8) have been obtained by the gas condensation synthesis method. The microstructural peculiarities and magnetic behaviour of the nanoparticles is analysed depending on the composition and thermal treatment. Collateral phases, which are difficult to detect by traditional methods, are identified. The 59Co,57Fe NMR and 57Fe Mossbauer spectroscopies have shown that homogeneity of the composition and removal of carbon from the metallic core can be reached by annealing. The combination of methods has quantified the fraction of superparamagnetic particles, the proportion of paramagnetic inclusions. A simplified visual interpretation of the 59Co NMR spectra is proposed for binary FeCo alloys.

Substantial progress in the area of nanotechnology requires special quality of magnetic nanoparticles. Conventional methods of analysis are not always efficient to the study of nanoparticles. This paper is dedicated to the problem of quantitative analysis of the phase composition of ferromagnetic nanoparticles and the fundamental issue of transition to the single domain magnetic state. A comprehensive study of Fe@C nanoparticles has been carried out, including local Fe-57 NMR and MOssbauer spectroscopy methods. It has been found that the cores of nanoparticles contain phases of alpha-iron, iron carbides, ferromagnetic and paramagnetic phases of iron-carbon FeCx solid solutions. Annealing of the nanoparticles leads to a significant redistribution of the phase composition and leads to an increase in magnetization. Also, a nanoscale effect has been found. It consists in observation of two lines in NMR spectra corresponding to multidomain and single-domain state. The hyperfine fields obtained by NMR and Mossbauer spectroscopy methods are discussed.

A resistance of cavitation erosion-corrosion of the AISI 420 martensitic stainless steel was evaluated in this study. The cavitation resistance of this stainless steel has been examined using an ultrasonic vibratory method by applying water-voltage combination effect. The curves of cumulative material loss and erosion rate were attained and discussed. In addition, surface topography and scanning electron microscope (SEM) micrographs have been utilized to characterize the eroded surface after the cavitation test. The results have been compared with previously obtained results for the AISI 1040 steel. The cavitation results showed that the AISI 420 steel has exhibited the better resistance to cavitation comparing with the AISI 1040 steel under the similar test conditions. The total cumulative material loss of the AISI 420 was approximately three times less than that of the AISI 1040. Surface topography and SEM micrographs showed that the severity of damage of the AISI 1040 was found to be a higher compared to that of the AISI 420 steel.

The 61Ni NMR spectra have been obtained in carbon encapsulated nickel nanoparticles. It has been shown that the cores of the particles consist of metallic nickel with face-centered cubic structure, nickel carbide Ni3C and carbo-nnickel solid solution. The carbon shell of nanoparticles is a highly defective structure and close to an amorphous glassylike carbon.

The 61Ni, 13C NMR spectra of carbon encapsulated nickel nanoparticles have been obtained. It has been shown that the cores of the particles consist of metallic nickel with face-centered cubic structure, nickel carbide Ni3C and carbon-nickel solid solution. The carbon shell of nanoparticles is a highly defective structure and close to an amorphous glassy-like carbon.