Publications on the project |
059 Effect of nonstoichiometry on the structure and microwave dielectric properties of Ba(Co1/3Nb2/3)O3 |
Authors: | A. G. Belous, O. V. Ovchar, A. V. Kramarenko, Bostjan Jancar, Jana Bezjak, Danilo Suvorov | |
Summary: | Polycrystalline nonstoichiometric Ba(Co1/3Nb2/3)O3 (BCN) materials have been synthesized and investigated. Deviations from stoichiometry have been shown to lead to the formation of crystalline Ba6CoNb9O30 (barium deficiency) and Ba8CoNb6O24 (cobalt deficiency). The effect of phase composition on the microwave dielectric properties of BCN has been studied. The results demonstrate that the dielectric properties of BCN-based materials can be tuned by varying cobalt content. The materials obtained are high-Q microwave dielectrics with temperature-stable properties. | |
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Edition: | Inorganic Materials | | | 2010,
598–603,Russian |
059 Low-Loss Microwave Dielectrics for Different Frequency Ranges |
Authors: | A. Belous, O. Ovchar | |
Summary: | Depending on the operating frequency range of modern communication systems various microwave elements
are required for effective operation of radio equipment. In this work potential ways of developing the microwave
dielectric materials for different frequency ranges are discussed. It has been shown that temperature stable
dielectrics with the permittivity of about 100, which are intended for the utilization in the decimetre wavelength
band, can be developed by means of alio- and isovalent substitution in the cation sublattices of barium lanthanide
titanates (BLTss) Ba6−xLn8+2x/3Ti18O54 (Ln = La–Gd). The temperature behaviour of the permittivity and
dielectric loss in the BLTss has been discussed in terms of both harmonic and anharmonic contributions to the
phonons of the BLT crystal lattice. It has been shown that a slight deviation from the compositional stoichiometry
in both A-site and B-site deficient perovskites Ba(M2+
1/3Nb2/3)O3 (M = Co, Zn, Mg) allows a prominent enhancement
of their microwave quality factor (Q). As a consequence, new dielectrics with the extremely high quality
factor (Qxf = 90 000–150 000 GHz), which are intended for the utilization in the centimetre wavelength band, can
be developed. Some examples of the possible implementation of the developed materials are also discussed. | |
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Edition: | Acta Physica Polonica A | | | 2010,
2217–2227,English |
059 Multiphase microwave dielectrics |
Authors: | A.G. Belous and O.V. Ovchar | |
Summary: | Several types of multiphase ceramic materials with excellent microwave (MW) dielectric properties have been considered. Studied materials were based on complex niobates and titanates with various crystal structures in which very high values of the MW quality factors (Q) can be attained. Slight compositional changes in the complex oxide systems have been shown to induce rather combined effect on the cation arrangement of separate crystal phases as well as on the microstructure and phase composition of multiphase ceramic materials. As a consequence, the ways to tailor MW dielectric parameters of the ceramics through a proper adjustment of both structure and distribution of enclosed phases have been presented and discussed. The examples of the multiphase MW dielectrics with enhanced properties have also been presented. | |
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Edition: | Materials Science-Poland | | | 2011,
47-55,English |
059 A-site deficient perovskites Ba(M2+ 1/3Nb2/3)O3: microstructural attributes for a high quality factor |
Authors: | O. Ovchar, D. Durylin, A. Belous, B. Jancar, Kolodiazhnyi | |
Summary: | Slight A-site deficiency in ordered perovskites Ba(M2+ 1/3Nb2/3)O3(M - Co, Zn, Mg) is shown to promote the formation of single-phase dense ceramics, in which the microwave (MW) quality factor Q attains its maximum values. Any further decrease in the Ba concentration in Ba(M2+ 1/3Nb2/3)O3 always results in the formation of a multiphase material containing secondary phase with the tetragonal tungsten bronze (TTB) structure. The amount of TTB phase in the perovskite matrix was found to depend on both the Ba concentration and the sintering temperature. The composition and properties of the TTB phase are discussed in terms of their effect on the MW dielectric parameters of Ba(M2+ 1/3Nb2/3)O3 ceramics. | |
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Edition: | Materials Science-Poland | | | 2011,
56-62,English |
059 Effect of Zn2TiO4 and ZnB2O4 additions on the microstructure and dielectric properties of AgNb1 − x Ta x O3 solid solutions |
Authors: | O. V. Ovchar, D. A. Durilin, A. G. Belous, Bostjan Jancar, Matjaz Spreitzer, Danilo Suvorov | |
Summary: | We report the preparation and characterization of AgNb0.6Ta0.4O3 (ANT) based materials. The addition of Zn2TiO4 and ZnB2O4 influences the sintering temperature, phase composition, and microstructure of ANT ceramics. ANT doped with 1 wt % Zn2TiO4 or ZnB2O4 has high dielectric permittivity (400–470), low dielectric losses (tanδ ∼ 10−3), and a nonlinearity coefficient n R ≅ 3–9% (at a field strength E = 3 × 106 V/m). | |
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Edition: | Inorganic Materials | | | 2011,
1357-1360,Russian |
059 Tetragonal tungsten bronzes in Ba(M2+1/3Nb2/3)O3 microwave ceramics |
Authors: | O. Ovchar, D. Durylin, A. Belous, V. Porokhonskyy, B. Jancar, T. Kolodiazhnyi | |
Summary: | For the first time, the dielectric properties of the 9:1:7 TTB phases Ba9M2+Nb14O45 (M = Co, Mg, Zn) which form in Ba-deficient high-Q perovskite niobates Ba(M2+ 1/3Nb2/3)O3 have been measured in the radio-frequency and microwave range. The low-temperature dielectric relaxation found in Ba9M2+Nb14O45 was shown to give a strong contribution into their microwave dielectric loss. The measured data were used for a simple simulation of the Q-factor of a perovskite-TTB composite. Calculated parameters have been shown to correspond well to the measured data | |
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Edition: | Ferroelectrics | | | 2012,
176-182,English |
059 Synthesis of nanoparticles and films BaTi1-xZrxO3 by sol-gel method |
Authors: | O. Ovchar, D. Durylin D.O., Suslov O.M., Solopan S.O., Belous A.G. | |
Summary: | Nanosize powders of solid solutions BaTi1–xZrxO3 (0.2 £ х £ 0.3) were synthesized by a sol–gel technique as well as the corresponding chemical reactions have been studied. Single-phase films of BaTi1–xZrxO3 were deposited on the a-Al2O3 substrates by a sol–gel technique as well as the influence of the gel concentrations and number of deposited layers on the films
production have been examined. Synthesized nanopowders were also utilized for the production of sintered ceramics which has been shown to demonstrate the potential for the implementation as non-linear dielectrics. | |
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Edition: | Ukrainian chemical journal | | | 2013,
7-12,Ukrainian |
059 Synthesis and Dielectric Properties of BaTi1-xZrxO3-based Ceramic and Film Materials |
Authors: | A. Suslov, D. Durilin, O. Ovchar, A. Belous, V. Bovtun, M. Kempa, B. Jancar, M. Spreitzer | |
Summary: | The process of formation of BaTi1-xZrxO3 solid solutions (0.2 ≤ × ≤ 0.5) with perovskite structure has been studied. The phase composition, microstructure and electrophysical properties of BaTi1-xZrxO3 ceramic and film materials have been investigated. It has been shown that when zirconium content of ceramic materials is increased, a decrease in permittivity (ε) and loss (tan δ) is observed. In this case, the nonlinearity factor (nR) retains high values (nR = 30-50 %) in relatively weak electric fields (E = 30-60 kV/cm). BaTi0.6Zr0.4O3 films have been obtained by sol-gel method. The dielectric properties of films in the microwave range have been investigated. | |
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Edition: | Proceedings IEEE ELNANO’2014 | | | 2014,
66-69,English |
059 Synthesis and Dielectric and Nonlinear Properties of BaTi1 – xZrxO3 Ceramics |
Authors: | A. N. Suslov, D. A. Durilin, O. V. Ovchar, A. G. Belous,
Bostjan Jancar, and Matjaz Spreitzer | |
Summary: | We have studied the formation of BaTi1 – xZrxO3 solid solutions with the perovskite structure. The
phase composition, microstructure, and electrical properties of the BaTi1 – xZrxO3 materials have been inves
tigated. The results demonstrate that their dielectric permittivity (ε) and loss tangent (tan δ) decrease
with increasing zirconium content. At the same time, their nonlinearity coefficient (nR) remains large (nR = 30–50%) in relatively low fields (E = 30–50 kV/cm). The present data suggest that the materials studied here are potentially attractive for use in creating nonlinear devices of modern
microelectronics. | |
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Edition: | Inorganic Materials | | | 2014,
1216-1221,Russian |
059 Polyesterification and complex formation in synthesis of titanates by sol-gel method |
Authors: | O Suslov, S. Kobylyanska, V. Trachevskiy, A. Belous | |
Summary: | Nanosized powders of solid solutions of lanthanum-lithium (LLTO) and barium-strontium (BSTO) titanates with perovskite structure have been obtained by sol-gel method. Model of coordination structure of polymers formed in the sol–gel system
have been proposed. It have been shown that using the sol-gel method of forming solid solutions occurs in a single step and at relatively low temperatures. | |
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Edition: | Ukrainian chemical journal | | | 2014,
21-25,Ukrainian |
059 Patent. Microwave dielectric composite material based on barium titanate and samarium |
Authors: | A.G.Bilous, O.V. Ovchar, D.O. Durylin, Y.D. Stupin | |
Summary: | The invention relates to the development of composite microwave dielectrics and can be used in the manufacture of high-profile filter elements and generating devices for telecommunications, cellular, microwave, radio navigation and radar communication systems. | |
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Edition: | Рatent №58005, published 15.07.2003 | | | 2011,
,Ukrainian |
059 059
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059 4. Nanomaterials Purpose: Expected results:Release of new product: technology Stage 1: Stage 2: Stage 3: Stage 4: Stage 5:
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