Strontium-barium niobate (SrxBa(1−x)Nb2O6) films can be considered as a promising material for microwave applications due to high dielectric nonlinearity and relatively low losses. Since strontium-barium niobate has a disordered structure that determines its unique electrical properties, the identification of structural features of the SrxBa(1−x)Nb2O6 films is the key to their successful use. The SrxBa(1−x)Nb2O6 films were synthesized on a sapphire substrate by magnetron sputtering. The structure of the films was studied by both traditional methods of electron microscopy, X-ray diffraction, and the rarely used for thin films investigation Brillouin light scattering method, which was the focus of our study. We show that Brillouin light scattering is an excellent nondestructive method for studying the structural features of thin ferroelectric strontium-barium niobate films. An analysis of the features of the Brillouin light scattering spectra in thin-film structures and their comparison with the spectra of bulk crystals allowed us to determine with high accuracy the thickness of the films under study and their structural features determined by the resonant scattering of acoustic waves.

A theoretical model is proposed that allows us to describe the processes of formation of the sputtered atom flow, transport of this flow in the target-substrate space and deposition of the substance onto the substrate during magnetron sputtering. The main difference between the presented model and the existing ones is the combined consideration of the spatial distribution of sputtered atoms and the temperature gradient in the working chamber during magnetron sputtering at high power. To verify the model, real technological parameters of deposition of metal films by magnetron sputtering were used, optimized to achieve a high film growth rate. The agreement between the calculated film thicknesses obtained as a result of modeling and the experimental data was no worse than 5% at discharge powers in the range of 100 – 700 W. Comparison of the experimental data with the simulation results showed that the model adequately describes the sputtering processes at high discharge powers and low pressures, in contrast to approaches that do not take into account the temperature gradient in the working space.

Thin films of strontium titanate, which have nonlinear properties that are promising for microwave applications, were grown on a polycrystalline aluminum oxide substrate using magnetron sputtering and high-temperature annealing. It was shown that the improvement of the film structure with an increase in the deposition temperature was clearly correlated with both an increase in nonlinearity and an improvement in the loss level. A capacitor based on an SrTiO3 film deposited at a deposition temperature of 900 °C and subjected to annealing demonstrated a tunability of 46% with a loss tangent of 0.009–0.014 at a frequency of 2 GHz. This was the first successful attempt to form a planar SrTiO3 capacitor on an alumina substrate, which exhibited a commutation quality factor of above 3000 in the microwave range.

This article presents a wide-angle-scanning leaky-wave antenna (LWA) based on a composite right/left-handed (CRLH) transmission line. In contrast to traditional semiconductor elements, thin-film ferroelectric capacitors were implemented in the CRLH unit cells to enable electric beam scanning. The proposed CRLH LWA has a single-layer design without metalized vias and is compatible with PCB and thin-film technologies. To fabricate the CRLH LWA prototype, dielectric material substrates and thin-film ferroelectric capacitors were manufactured, and their characteristics were investigated. Double-sided metalized fluoroplast-4 reinforced with fiberglass with a permittivity of 2.5 was used as a substrate for CRLH LWA prototyping. A solid solution of barium strontium titanate (BaxSr1−xTiO3) with a composition of x=0.3 was used as a ferroelectric material in electrically tunable capacitors. The characteristics of the manufactured ferroelectric thin-film capacitors were measured at a frequency of 1 GHz using the resonance method. The capacitors have a tunability of about two and a quality factor of about 50. The antenna prototype consists of ten units with a total length of 1.25 wavelengths at the operating frequency of close to 2.4 GHz. The experimental results demonstrate that the main beam can be shifted within the range of −40 to 16 degrees and has a gain of up to 3.2 dB. The simple design, low cost, and excellent wide-angle scanning make the proposed CRLH LWA viable in wireless communication systems.

Barium-strontium niobate in thin film form can be considered as a prospective ferroelectric material for microwave applications due to high dielectric nonlinearity. Its performance is linked to film structure quality, and one method to achieve high-quality films on microwave substrates goes through the process of annealing. (Sr,Ba)Nb2O6 films of good crystallinity were formed on sapphire and alumina substrates by magnetron sputtering. The processes of recrystallization of films on single- and polycrystalline substrates under the conditions of ex situ annealing at temperatures of 1100-1200 degrees C were studied. Highly (00l) oriented films on sapphire substrate were obtained by the deposition in oxygen atmosphere at a substrate temperature of 900 degrees C with post-growth annealing in air at an annealing temperature of 1150 degrees C.

Thin films of strontium titanate, which reveal high structure quality and tunable properties prospective for microwave applications at room temperature, were grown on a semi-insulating silicon carbide substrate using magnetron sputtering for the first time. The films’ growth mechanisms were studied using medium-energy ion scattering, and the films’ structures were investigated using X-ray diffraction. The electrical characteristics of planar capacitors based on strontium titanate films were measured at a frequency of 2 GHz using a high-precision resonance technique. It is shown that the tendency to improve the crystalline structure of strontium titanate film with an increase in the substrate temperature is most pronounced for films deposited at elevated working gas pressure under low supersaturation conditions. Planar capacitors formed on the basis of oriented SrTiO3 films on silicon carbide showed tunability n = 36%, with a loss tangent of 0.008–0.009 at a level of slow relaxation of capacitance, which is significantly lower than the data published currently regarding planar tunable ferroelectric elements. This is the first successful attempt to realize a planar SrTiO3 capacitor on a silicon carbide substrate, which exhibits a commutation quality factor more than 2500 at microwaves.

Polymer dielectric composites consisting of polytetrafluoroethylene, silicon dioxide and barium titanate mixed in various proportions were successfully synthesized by low-temperature sintering. The structure of the obtained composite samples was studied by the X-ray diffraction, the electron microscopy, and the weight method. Electrical characteristics (dielectric permittivity and losses) of samples were investigated at a frequency of 1 MHz. According to structural analysis, the synthesized samples are a mixture of amorphous polytetrafluoroethylene and silicon dioxide, and crystalline ferroelectric BaTiO3, the ratio of which determines the electrical properties of the composites. Depending on the content of barium titanate, the studied samples show a permittivity from 4 to 6.5 with a dielectric loss level of 0.06–0.14. It is shown that the significant influence on the dielectric properties of the polytetrafluoroethylene/silicon dioxide/barium titanate system is exerted by heat treatment modes.

We presented the results of a study of the structural and electrical properties of ferroelectric composites based on barium and strontium titanates with the addition of boric anhydride synthesized by low-temperature sintering. The obtained materials are promising as a basis for the implementation of electrically controlled metamaterials with volumetric ferroelectric inhomogeneities.

The structural and electrical properties were studied in ferroelectric composites based on barium and strontium titanates with the addition of boric anhydride, which were synthesized by low-temperature sintering. The obtained materials are promising for creating electrically controlled metamaterials with bulk ferroelectric inhomogeneities.

The authors were not aware of errors made in the proofreading phase, and, hence, wish to make the following corrections to this paper [...]

Polymer dielectric composites consisting of polytetrafluoroethylene, silicon dioxide and barium titanate mixed in various proportions were successfully synthesized by low-temperature sintering. The structure of the obtained composite samples was studied by the X-ray diffraction, the electron microscopy, and the weight method. Electrical characteristics (dielectric permittivity and losses) of samples were investigated at a frequency of 1 MHz. According to structural analysis, the synthesized samples are a mixture of amorphous polytetrafluoroethylene and silicon dioxide, and crystalline ferroelectric BaTiO 3 , the ratio of which determines the electrical properties of the composites. Depending on the content of barium titanate, the studied samples show a permittivity from 4 to 6.5 with a dielectric loss level of 0.06–0.14. It is shown that the significant influence on the dielectric properties of the polytetrafluoroethylene/silicon dioxide/barium titanate system is exerted by heat treatment modes.

Thin ferroelectric barium-strontium titanate (BST) films of high structure quality have been grown on semi-insulating silicon carbide substrates. The crystal structure and elemental composition of the obtained films were studied by the X-ray diffraction and Medium Energy Ions Scattering. Planar capacitors based on these BST films reveal the combination of high tunability and low losses at microwaves. 30 GHz ferroelectric phase shifter demonstrating a figure of merit of 22 deg/dB with a phase shift of & UDelta;& phi; = 220 deg is implemented based on BST films on silicon carbide substrate.

(Sr,Ba)Nb2O6 (SBN) relaxor ferroelectric thin films exhibiting nonlinear properties promising for microwave applications were grown on a polycrystalline aluminum oxide substrate for the first time. Films of good crystallinity were obtained using the sputtering technique and high-temperature annealing. For all films, a significant change in the phase composition after high-temperature treatment was observed, and annealing provided a different effect on the phase composition of films deposited at different substrate temperatures. Tunable properties of the SBN films were investigated as a function of the deposition temperature and annealing conditions using planar capacitors with microwaves. The capacitor based on the strontium barium niobate film deposited at a temperature of 950 °C and subjected to annealing demonstrates a tunability of 44% and a loss tangent of 0.009 ÷ 0.022, which is expressed in the microwave commutation quality factor of 1740. This is the first successful attempt to form planar capacitive structures based on SBN films, which reveal a commutation quality factor above 1000 for tunable microwave applications.

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 successfully synthesized and incorporated into the periodic holes of the ferrite matrix to build the meta-structure. Investigation of the structure showed dielectric permittivity, which increased with the volume of ferroelectric inclusions. The range of magnetically controlled interactions of the meta-structures with an electro-magnetic field was increased for the matrix with periodic holes filled by the ferroelectric composite in comparison with the basic ferrite matrix. The ferrite substrate completely determined the microwave losses of the sample and the ferroelectric inclusions increased the Q-factor of the meta-structure.

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 holes of dielectric matrix to form tunable metamaterial structure. The studied composite samples showed a relative dielectric permittivity of 18 with a dielectric loss level of 0.02 at a frequency of 2 GHz. The tunability of the entire structure under the applied electric field of 2 V/mu m was 4%, which is a promising result for microwave tunable applications.

A method is proposed for ion-plasma deposition of thin multicomponent films with the ability to control the component composition in thickness (graded film) with a change in the pressure of the working gas according to a given law. Using the Ba x Sr 1-x TiO 3 (BSTO)perovskite-type structure as an example, the calculated (Monte Carlo simulation) and experimental dependences of the component composition of films and their deposition rate on the pressure of the working gas were obtained. As an example, the possibility of deposition of BSTO films with a linear distribution of composition by their thickness. Keywords: ion-plasma deposition, thin multicomponent films, composition control.

A method is proposed for ion-plasma deposition of thin multicomponent films with the ability to control the component composition in thickness (gradedfilm) with a change in the pressure of the working gas according to a given law. Using the BaxSr1-xTiO3 (BSTO)perovskite-type structure as an example, the calculated (Monte Carlo simulation) and experimental dependences of the component composition of films and their deposition rate on the pressure of the working gas were obtained. As an example, the possibility of deposition of BSTO films with a linear distribution of composition by their thickness.

In this study, the structural and microwave properties of BaTiZrO3 films deposited on alumina substrate were investigated. The films were deposited by RF magnetron sputtering in Ar/O2 ambient atmosphere. The research of the island films at the initial stages of the growth showed that the pyramidal type of growth prevails. It was demonstrated that as-deposited film is a BaZrTiO3 solid solution with a deficiency of titanium compared to the target. The air annealing at temperatures of 1100–1200 °C leads to the formation of a well-formed crystalline solid solution of BaZr0.3Ti0.7O3 with a predominant orientation (h00). The investigation of microwave parameters of the films fabricated at different conditions showed that the best performance with the tunability of 4.6 (78%), and the Q-factor of 18 to 40 at 2 GHz was achieved at annealing temperature of 1150 °C.

Introduction. An experimental study of the structural and electrophysical properties of multicomponent films of solid solutions of barium titanate-zirconate and barium titanate-stannate on sapphire substrates has been carried out. These materials are an alternative to the more studied barium-strontium titanate for use in microwave technology, due to the relatively high controllability. In this paper, it is shown that when using post-post high-temperature annealing, films with a component composition close to the composition of the sprayed targets are formed on the substrate. Optimal deposition temperatures of thin films of barium titanate-zirconate and barium titanate-stannate have been determined to obtain the best electrophysical parameters.Aim. Investigation of structural and microwave properties of BaZrxTi1-xO3 (BZT) and BaSnxTi1–xO3 (BSnT) films on dielectric substrates. These ferroelectric materials are promising in terms of losses and nonlinearity, and the formation of planar structures based on these materials on a dielectric substrate allows for a significantly higher level of operating power of the microwave device.Materials and methods. The crystal structure and phase composition of the obtained films were studied by X-ray diffraction using a DRON-6 diffractometer on the emission spectral line CuKa1 (λ = 1.5406 Å). Capacitance C and Q-factor (Q = 1/tg δ) of capacitors were measured at frequencies of 1 and 3 GHz using a resonator and an HP 8719C vector analyzer.Results. It is established that high-temperature annealing after film deposition has a significant effect on the crystal structure, phase composition of films and their electrical characteristics. For the first time, a low level of dielectric losses of planar capacitive elements based on titanate-stannate and barium titanate-zirconate films in the frequency range of 1…60 GHz with acceptable controllability has been demonstrated.Conclusion. The results obtained indicate the prospects of using thin ferroelectric films of BaSn0.5Ti0.5O3 and BaZr0.5Ti0.5O3 solid solutions in microwave devices.