Olga Yu. Sinelshchikova

Institute of Silicate Chemistry, Russian Academy of Sciences (ISC RAS)

Meta-structures based on periodic ferroelectric inhomogeneities in a dielectric matrix were implemented, which demonstrated tunability at a relatively low effective dielectric permittivity and low microwave losses. Glass-ceramic composite consisting of low melting glass and barium-strontium titanate was successfully incorporated into the periodic h...

A metamaterial based on periodic ferroelectric inhomogeneities in a magnetic ferrite matrix including a quantity of ferroelectric composite in a matrix, demonstrating relative low microwave losses and effective dielectric permittivity, was produced. Glass-ceramic composites, consisting of low-melting glass and barium-strontium titanate, were succes...

Introduction . Materials exhibiting high dielectric permittivity are relevant for use in modern ultrahigh-frequency electronics. Among them, ferroelectrics with high dielectric nonlinearity present particular interest. The electrical strength of ferroelectric materials can be increased using modern composite structures based on mixing ferroelectrie...

Magnetoelectric composites consisting of barium-strontium titanate and nickel ferrite mixed in various proportions were successfully synthesized by low-temperature sintering. The crystal structure of the obtained samples was studied by the X-ray diffraction and the electron microscopy. Magnetic and electrical characteristics of as-prepared and anne...

Hollandite-based ceramics are mainly produced by the traditional solid-phase method. However, the use of “wet” chemistry can improve its morphological characteristics, increase porosity, etc., as well as change the electrophysical properties. In this study complex oxides with hollandite-type structure in the system K2O–MeO–TiO2 (Me = Mg, Ni, Cu) we...

Glass-ceramic composites consisting of potassium-iron-silicate glass and barium titanate mixed in various proportions were successfully synthesized by low-temperature sintering. The crystal structure of the obtained composite samples, the porosity and the microhardness were studied by the X-ray diffraction, the electron microscopy, the weight metho...

In this work, titanate Cs 2 Fe 2 Ti 6 O 16 with a hollandite-type structure was synthesized by solid-phase synthesis. The electrical conductivity of the obtained ceramics was investigated in the temperature range from 25 to 800 °C in air and in the presence of an argon-hydrogen mixture (3% H 2 ). It was found that the electrical conductivity of the...

In this work, nanocrystalline yttrium orthochromite (YCrO3) was synthesized via the solution combustion method using metal nitrates and glycine. The resulting powder was used for sintering YCrO3 porous ceramics. The SEM, EDX, PXRD and TMA were used to examine structural and morphological features of both the preceramic powder and the sintered ceram...

Based on porous silicate glasses obtained by ion exchange, glass-ceramic materials containing a solid solution of barium-strontium titanate with a dielectric constant of more than 100 at microwaves, were synthesized for the first time. Glass-ceramic structures were studied using X-ray diffraction, secondary electron microscopy, Mössbauer spectrosco...

New composite solid electrolytes formed in the SrO–Bi2O3–Fe2O3 system have been studied. The total electrical conductivity of the composites synthesized via the solid-phase method increases with an increase in the Fe2O3 content, being of mixed ion-electronic nature. Dependence of the fraction of ionic conductivity on the composition has been establ...

New composite solid electrolytes formed in the SrO–Bi2O3–Fe2O3 system have been studied. The total electrical conductivity of the composites synthesized via the solid-phase method increases with an increase in the Fe2O3 content, being of mixed ion-electronic nature. Dependence of the fraction of ionic conductivity on the composition has been establ...

New composite solid electrolytes formed in the SrO–Bi2O3–Fe2O3 system have been studied. The total electrical conductivity of the composites synthesized via the solid-phase method increases with an increase in the Fe2O3 content, being of mixed ion-electronic nature. Dependence of the fraction of ionic conductivity on the composition has been establ...

Materials with strong susceptibility with respect to the electromagnetic field, namely, ferroelectric (FE) and ferromagnetic (FM) materials are of great interest for modern electronics. On the basis of ferroelectrics, devices such as varicades, delay lines, phase shifters, etc. are being actively developed. Ferromagnets (primarily ferrites) serve a...

The results of the study of the interaction of an aqueous solution of strontium nitrate with potas-sium-titanate nanoparticles of different morphology obtained by the hydrothermal method are reported. Comparative analysis showed the advantage of nanotubes as sorbents over nanolayers and nanowires. As can be seen from the experiment conducted with n...

The results of the study of novel composite solid electrolytes based on the CаO–Bi2O3–Fe2O3 system are presented. These materials have a mixed electronic-ionic conductivity which increases with the growth of the Fe2O3 content. In the (СаO)0.26(Bi2O3)0.74–Fe2O3 section, a part of the oxygen-ionic component increases with an increase in the Fe2O3 con...

This work presents the results of investigating the catalytic activity of potassium titanate nanomaterials doped by different metals (Ni, Mg, Al, Fe, and Cr) in oxidation reactions of hydrogen and carbon monoxide. It is shown that the best characteristics of the oxidation of the investigated gases have nanotubes doped by aluminium (0.3 × 10–5 mol H...

Study of the phase formation in the systems TiO2‒MO(M2O3)‒KOH‒H2O (M = Mg, Ni, Al) from crystalline and coprecipitated X-ray-amorphous mixtures demonstrated that doped potassium titanate nanotubes can be obtained in a hydrothermal treatment of coprecipitated hydroxides in the temperature range 170‒220°C. The average outer diameter of the thus synth...

Electric properties of diphosphates Na2ZnP2O7, K2ZnP2O7, K2Zn3(P2O7)2, Li12Zn4(P2O7)5, Li2x Zn2–x P2O7 (0.30 < x ≤ 0.56), Li2ZnP2O7, and Li4P2O7 with one alkaline cation; LiNaZnP2O7, LiKZnP2O7, Na2–x Kx ZnP2O7 (0.0 < x ≤ 0.6), Nax K2–x ZnP2O7 (0 < x ≤ 0.54), and Na1–x K1 + x ZnP2O7 (0 ≤ x ≤ 0.1) with two alkaline cations; and solid solutions LiNa1–...

A new method of sol–gel synthesis has been proposed for fabrication of functional materials with ramsdellite and hollandite types of crystal structure in the following oxide systems: Me2O–Me′2O3–Me″O2 (Me = Li, K; Me′ = Ga, Cr, Fe, In; Me″ = Ti, Sn). The formation of titanates with ramsdellite-type structure is shown to achieve at the temperature r...

The results of experimental studies of synthesis of the hollandite phase K2Ga2Ti6O16 using initial mixtures of different dispersion compositions obtained by two methods, i.e., mechanical dispersion (MD) (followed by solid-phase sintering) and sol-gel method (Pechini method, MP), are reported. The catalytic properties of the obtained materials in th...

The mechanism of solid-phase interaction in synthesis of BaTi4O9 is investigated using initial mixtures characterized by different degrees of dispersion and prepared by three methods: (i) mechanical mixing and grinding of initial components, (ii) coprecipitation from aqueous solutions of salts, and (iii) the citrate-nitrate sol-gel technique. The u...

This paper reports on the results of experimental investigations of solid solutions that have a ramsdellite structure and crystallize in the Li2O-Fe2O3-SnO2-TiO2, Li2O-Fe2O3-TiO2, and Li2O-Cr2O3-TiO2 systems. The concentration boundaries of existence of these solid solutions are determined, and their thermal and electrical properties are studied. I...

The mechanism and kinetics of formation of solid solutions based on hollandite in the BaO(Cs2O)-Al2O3-TiO2 system are investigated using the initial mixtures prepared by two methods: (i) mechanical grinding and mixing of the initial components and (ii) coprecipitation from aqueous solutions of the salts. It is established that the mechanism of form...

The mechanism of formation of barium titanate Ba2Ti9O20 in the BaO-TiO2 and BaO-SrO-TiO2 systems is investigated using initial mixtures prepared by three methods, namely, mechanical grinding of the initial reactants, coprecipitation from aqueous solutions of salts, and the sol-gel technique. It is established that, irrespective of the preparation p...

The ramsdellite-type phases crystallizing in the Li2O-Fe2O3-TiO2 system in the course of synthesis in gaseous media at different oxygen partial pressures are studied. Solid solutions based on the ramsdellite structure with the composition Li2Ti3−x Fex O7 − δ (0 ≤ x ≤ 0.7) are prepared in an oxidizing medium (P O2 = 1 atm) for the first time. Analys...

The phase relationships in binary, ternary, and more complex Me2+O–Me2+O–Me23+O3–Me4+O2–TiO2 systems (Me+ = Li+, K+, Rb+, Cs+; Me2+ = Mg2+, Sr2+, Ba2+, Zn2+; Me3+ = Al3+, Fe3+, Ga3+; Me4+ = Sn4+, Zr4+) are investigated in the concentration regions corresponding to the compositions of titanates with a tunnel structure: Li2(Me2+,Me3+)y(Me4+,Ti)4O8 ra...

This paper presents the results of analyzing the influence of synthesis methods, namely, the solid-phase interaction and coprecipitation, on the mechanism of formation, the degree of sintering, and the dielectric properties of barium titanate Ba2Ti9O20. The effect exerted by ZrO2 and SrO additives on the solid-phase synthesis is investigated. It is...

The possibility of forming hollandite-type phases during the solid-phase reaction in the Cs2O(MeO)–Al2O3–TiO2 (Me = Ba, Sr) systems is studied. It is revealed that, in the Cs2O–BaO–Al2O3–TiO2 system, the region of existence of Csx Ba1 – x/2Al2Ti5O14 solid solutions with a hollandite-type structure lies in the concentration range 0 ≤ x ≤ 0.7. In the...

The mechanism of solid-phase interaction in the BaO–TiO2(ZrO2) and Cs2O–BaO–TiO2(ZrO2) systems is investigated. It is established that the formation of the Ba2Ti9O20 compound and Ba2Ti9O20-based solid solutions is a multistage process proceeding through the formation of intermediate phases. The solid-phase interaction in the BaO–TiO2(ZrO2) system o...