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Introduction of dopants is a classic method for modifying the properties of materials, in particular, complex oxides of the perovskite family with the general formula ABO3. Ions located in positions A and/or B are substituted. In this case, their valence can coincide with the valence of the basic ion (isovalent substitution) or differ (heterovalent substitution). Sodium niobate (NaNbO3) is a convenient basis for producing ferroelectric solid solutions. Doping changes the properties of sodium niobate in a wide range, allowing the production of functional materials for various applications. In this paper, the effect of Bi3+ doping upon substitution of niobium ion Nb5+ on the structure and electrophysical properties of sodium niobate is studied. It has been shown that such compositions are characterized by a significant increase in electrical conductivity with increasing the doping concentration, a decrease in the Curie temperature, and a change in the grain structure. The dopant concentration is more than 10 mol. % leads to the formation of some secondary phases.

The work is devoted to investigation of the influence of the technology for producing potassium sodium niobate ceramics with an acceptor impurity Ti4+ on its structure and dielectric properties. The aim of the work was to determine ways to obtain a single-phase composition of doped ceramics and the role of the TiO2 modifying impurity. It is shown that the substitution of niobium by titanium for preserves the cubic shape of potassium sodium niobate grains, increases dielectric losses and causes significant migration polarization. The latter leads to the fact that the maximum temperature dependence of the dielectric permittivity at low frequencies is not observed for the studied ceramics. The shift of the phase transition temperature caused by doping is not observed. In all samples, despite the heterogeneity of the elemental composition and grain structure, the phase transition temperature corresponds to the phase transition temperature of pure potassium sodium niobate ceramics.

The work presents the results of green synthesis (biosynthesis) of silver nanoparticles using aqueous extracts of maple and oak leaves. The efficiency of the synthesis, size and shape of the formed nanoparticles were studied using UV-visible spectroscopy, dynamic light scattering, atomic force microscopy and scanning electron microscopy techniques. It was found that the formation of silver nanoparticles is accompanied by the appearance of a plasmon resonance band in the electronic spectra of aqueous extracts, the maximum of which depends on the concentration of silver nitrate and is in the range of ~420-429 nm in the spectra of maple leaves, and in the spectra of oak extracts there is a shift towards longer wavelengths ~425-435 nm, which correspond to the formation of nanoparticles of larger size. According to the dynamic light scattering data, the size of nanoparticles in the maple extracts is of about 60-68 nm and in the oak samples of ~107 nm. The differences in the size and shape of nanoparticles obtained in the maple and oak phytoextracts detected by atomic force microscopy and scanning electron microscopy are explained by the different composition of bioactive substances in the plants involved in the reduction of silver ions and stabilization or modification of the surface of silver nanoparticles.

The paper describes the results of the scanning electronic and atomic force microscopy research of the surface structure of the Ni57Mn21Al22, Ni57Mn21Al19Si3, Ni40Co10Mn34Al16 rapidly quenched ribbons. The influence of the chemical composition on the size, boundary geometry and structure of the grains is considered. It is shown that all the test samples have a nano-sized martensitic relief, and its parameters are determined. It has been established that the cross section of the ribbon is represented by crystalline grains of different shapes which are due to differences in the cooling rates along the edges and in the center of the samples. Elemental mapping of the cross-sectional surface of the ribbons was carried out using an X-ray energy dispersive spectrometer, and a uniform distribution of chemical elements in the samples was established. It is shown that the cobalt doping of Ni57Mn21Al22 ribbon causes changes in the micromorphology of the surface and has a significant effect on the magnetic properties of rapidly quenched ribbons: field dependences of themagnetization and domain structure.

Introduction of dopants is a classic method for modifying properties of perovskite complex oxides of the family of general formula ABO3 . Sodium niobate NaNbO3 is widely used as a basis for creating solid solutions. The introduction of substitutional cations is carried out at both position A and at position B. Of particular interest is the case when valence of the dopant is greater or less than valence of the initial cation at the site. In this case, a defected structure is formed, which may have unique properties. This work is devoted to study of the electrical properties of sodium niobate ceramics doped with Fe3+. The substitution was carried out according to positions of the nibium cations Nb5+. It is shown that such compositions are characterized by a significant increase in electrical conductivity, a decrease in the Curie temperature, and a diffuse of the phase transition.