Extremely polysubstituted magnetic material based on magnetoplumbite with a hexagonal structure: Synthesis, structure, properties, prospects

Crystalline high-entropy single-phase products with a magnetoplumbite structure with grains in the µm range were obtained using solid-state sintering. The synthesis temperature was up to 1400 °C. The morphology, chemical composition, crystal structure, magnetic, and electrodynamic properties were studied and compared with pure barium hexaferrite BaFe 12 O 19 matrix. The polysubstituted high-entropy single-phase product contains five doping elements at a high concentration level. According to the EDX data, the new compound has a formula of Ba(Fe6Ga1.25In1.17Ti1.21Cr1.22Co1.15)O19. The calculated cell parameter values were a = 5.9253(5) Å, c = 23.5257(22) Å, and V = 715.32(9) Å3. The increase in the unit cell for the substituted sample was expected due to the different ionic radius of Ti/In/Ga/Cr/Co compared with Fe3+. The electrodynamicmeasurements were performed. The dielectric and magnetic permeabilities were stable in the frequency range from 2 to 12 GHz. In this frequency range, the dielectric and magnetic losses were??0.2/0.2. Due to these electrodynamic parameters, this material can be used in the design of microwave strip devices. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The work was supported by the Russian Science Foundation, project No. 18-73-10049

Magnetic and microwave properties of SrFe12O19/MCe0.04Fe1.96O4 (M = Cu, Ni, Mn, Co and Zn) hard/soft nanocomposites

This paper reports the synthesis, structural characteristics and magnetism of SrFe12O19/MCe0.04Fe1.96O4 (M = Cu, Ni, Mn, Co and Zn) hard/soft nanocomposites. The hard/soft compositions were manufactured via a one-pot reactions citrate sol-gel approach. The hard/soft phases formation was confirmed using XRD, SEM, TEM and HRTEM techniques. M vs. H (Magnetization measurements) were done at unbent temperature and 10 K. Smoothed M against H loops and single peaks in dM/dH vs. H curves were noticed in SrFe12O19/MnCe0.04Fe1.96O4, SrFe12O19/CuCe0.04Fe1.96O4 and SrFe12O19/ZnCe0.04Fe1.96O4 hard/soft nanocomposites. This indicated the manifestation of well exchange-coupled effect among hard and soft phases in these composites. However, SrFe12O19/CoCe0.04Fe1.96O4 and SrFe12O19/NiCe0.04Fe1.96O4 hard/soft nanocomposites showed non-well smoothed M against H loops and two peaks in dM/dH versus H plots, indicating that the dipolar interactions are unimportant compared to exchange-coupling behavior. Among all prepared nanocomposites, the SrFe12O19/MnCe0.04Fe1.96O4 hard/soft nanocomposite showed the highest exchange-coupling behavior. Microwave properties of the SrFe12O19/MCe0.04Fe1.96O4 (M = Cu, Ni, Mn, Co and Zn) hard/soft nanocomposites were investigated using coaxial method with applied frequency values fall between 2 and 18 GHz. Reflection losses were calculated from frequency dependences of the imaginary and real parts of permeability and permittivity. The correlation between the chemical composition of the spinel phase (A-cation) and microwave properties of composites. Most intensive electromagnetic absorption was observed for Ni- and Mn-spinels. This is can be a result of the differences in electron shell configuration and radii for A-site ions in the spinel phase. Change of the absorption mechanisms (transition from ionic polarization to dipole polarization) was observed. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).The work was supported by the Russian Science Foundation (agreement number 19-72-10071 ). Also Authors are thank to the Institute for Research & Medical Consultations (Projects Application No. 2018-IRMC-S-2 ) of Imam Abdulrahman Bin Faisal University (IAU – Saudi Arabia) for financial and technical supports

Alterations in the magnetic and electrodynamic properties of hard-soft Sr0.5Ba0.5Eu0.01Fe12O19/NixCuyZnwFe2O4 nanocomposites

Hard/soft (H/S) Sr0.5Ba0.5Eu0.01Fe12O19/NixCuyZnwFe2O4 nanocomposites (NCs) were produced via a one-pot sol–gel auto-combustion procedure. Phase and surface analyses were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HR-TEM). Magnetization measurements for H/S NCs with different x, y, and w ratios were investigated at two different temperatures (300 and 10 K). The M−H curves were not smooth for the different H/S NCs, revealing that the exchange interaction was incomplete. The derivative of the magnetization (dM/dH versus H) exhibited two separate peaks, confirming the non-coupled H/S mixtures. Maximum saturation magnetization (Ms) values of 93.9 and 63.1 emu/g were obtained at 10 and 300 K, respectively, for the H/S Sr0.5Ba0.5Eu0.01Fe11.99O19/Ni0.3Cu0.3Zn0.4Fe2O4 NC, which contained the highest content of Zn and the same contents of Ni and Cu within the soft magnetic phase. The calculated squareness ratios (SQR = Mr/Ms) were less than 0.5, indicating incomplete exchange coupling. The coercive field (Hc) of the produced NCs reached a maximum value of approximately 2485 Oe at 300 K and 2331 Oe at 10 K with a decrease in the Ms values to 56.9 emu/g at 300 K and 78.5 emu/g at 10 K for the H/S Sr0.5Ba0.5Eu0.01Fe11.99O19/Ni0.8Cu0.1Zn0.1Fe2O4 NC, which contained lower fractions of Zn and Cu and the highest fraction of Ni. The reflection/transmission-based waveguide approach was employed to investigate the electrodynamic properties of the H/S NC samples within a frequency band of 7–18 GHz. The reflection and transmission coefficients (S11/S21) were measured using a vector network analyzer (VNA) for the sample placed inside a waveguide. The frequency dispersions of the magnetic permeability and electric permittivity were calculated. © 2021 The Author(s)2020-164-IRMC; King Fahd University of Petroleum and Minerals, KFUPM; Russian Science Foundation, RSF: 21-79-10115This study was supported by the Deanship of Scientific Research of Imam Abdulrahman Bin Faisal University (Dammam, Saudi Arabia) through Grant No. 2020-164-IRMC . The authors also acknowledge support from the Center for Communication Systems and Sensing at KFUPM . Electromagnetic measurements and analysis were partially supported by the Russian Science Foundation (Agreement No. 21-79-10115)

Specific features of volume-modular technology application in the design of microwave electronic devices

Поступила: 10.05.2021. Принята в печать: 17.05.2021.Received: 10.05.2021. Accepted: 17.05.2021.State of problem. Today a significant part of passive microwave electronic devices is implemented in the form of single-layer structures. In some cases such approach leads to an increase in the overall dimensions characteristics of electronic equipment. Moreover the application of singlelayer microwave boards leads to the complexity of replacing individual functional units. Therefore the replacement of the entire microwave board is required to improve any of its functional part. It is nonprofit economically and inefficient technologically. Significant progress in eliminating the above mentioned disadvantages may be achieved by the application of volume-modular technology of design microwave electronic devices. Purpose. The purpose of the research is to present a brief overview of the features of the application of volume-modular technology in the design of microwave electronic devices of modern radio-electronic equipment. The volume-modular way of implementing microwave devices is described. It allows improving their weight and overall dimension characteristics and at the same time maintaining and increasing their functionality. The basic principles of design of volumemodular microwave electronic devices are formulated. The results of numerical simulation of the electrodynamics characteristics of a strip-slot transition are presented. The method for quantitative assessment of the influence of volume-modular technology on the weight and dimensions characteristics of microwave electronic devices is considered. The main advantages and disadvantages of volume-modular technology are listed. Results. We demonstrate a possibility of reducing the overall dimensions characteristics of passive microwave electronic devices by more than 10 times while maintaining their electrical parameters. Each component is presented in the form of a structurally separate and complete board with unified overall and connecting dimensions. The standard electromagnetic coupling between functional parts makes it possible to assemble microwave electronic devices with specified electrodynamics characteristics from the base elements.В статье представлен краткий обзор об особенностях применения объемно-модульной технологии в проектировании СВЧ электронных устройств современного радиоэлектронного оборудования. Описывается объемно-модульный способ реализации СВЧ устройств, позволяющий улучшить их массогабаритные характеристики и при этом сохранить и увеличить их функциональные возможности. Сформулированы основные принципы построения объемно-модульных СВЧ электронных устройств и приведены результаты численного моделирования электродинамических характеристик полосково-елевого перехода – основного базового их элемента. Рассмотрен способ количественной оценки влияния объемно-модульной технологии на массогабаритные характеристики СВЧ электронных устройств. Перечислены основные преимущества и недостатки объемно-модульной технологии

Features of Structure, Magnetic Sstate and Electrodynamic Performance of SrFe12−xInxO19

Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84–0.65 μm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types. © 2021, The Author(s).Investigations were performed under financial support from the Russian Science Foundation (Agreement No. 19-19-00694 of 06 May 2019)

Features of structure, magnetic state and electrodynamic performance of SrFe12-xInxO19

Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84-0.65 μm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.Investigations were performed under financial support from the Russian Science Foundation (Agreement No. 19-19-00694 of 06 May 2019).With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

Functional sr0.5ba0.5sm0.02fe11.98o4/x(ni0.8zn0.2fe2o4) hard-soft ferrite nanocomposites: Structure, magnetic and microwave properties

This paper reports the correlation between the composition of the functional Sr0.5Ba0.5Sm0.02Fe11.98O19/x(Ni0.8Zn0.2Fe2O4) hard-soft nanocomposites (SrBaSmFe/x(NiZnFe) NCs), where 0.0 ≤ x ≤ 3.0, and their structural features, magnetic, and microwave properties. SrBaSmFe/x(NiZnFe) hard/soft ferrite NCs are produced using the one-pot citrate combustion method. According to the XRD analysis, all samples showed the co-existence of both SrBaSmFe and NiZnFe phases in different ratios. Magnetic properties are measured in a wide range of magnetic fields and temperatures (10 and 300 K) and correlated well with the composition of the investigated samples. The microwave properties (frequency dispersions of the magnetic permeability, and electrical permittivity) are discussed by using the co-axial method in the frequency range of 0.7-18 GHz. Non-linear dependences of the main microwave features were observed with varying of composition. The microwave behavior correlated well with the composite theory. These results could be used in practice for developing antenna materials. © 2020 by the authors.This work was financially supported by the Deanship for Scientific Research (Project application No. 2020-164-IRMC) of Imam Abdulrahman Bin Faisal University (IAU—Saudi Arabia). The work was partially supported by the Russian Science Foundation (Agreement No. 19-72-10071 from 06 August 2019)

Fabrication of exchange coupled hard/soft magnetic nanocomposites: Correlation between composition, magnetic, optical and microwave properties

This paper studied the exchange coupling performance beside structural and microwave properties of SrFe12O19 (SFO) and x(CoTm0.01Tb0.01Fe1.98O4) (CoTmTb) (x ≤ 3.0) hard/soft ferrites nanocomposites (NCs). The structure and morphology of NCs were investigated by XRD, SEM, TEM and HR-TEM. Diffuse reflectance spectroscopic (DRS) measurements were applied on hexagonal ferrite, on spinel ferrite nanoparticles and on hard/soft NCs to specify the optical properties. Estimated Eg data are in a range between 1.32 and 1.79 eV. The magnetic properties were also inspected via measurements of magnetization (M) against magnetic field (H) at 300 K (RT) and 10 K (LT). The measurements performed at RT along with the plots of dM/dH versus H indicated that the NCs display good magnetic properties (exchange coupling behavior). The magnetic parameters such as (Ms, Mr, and Hc) show an enhancement in their values with an increasing the soft content at RT. Similarly, the maximum energy product (BH)max rises and reaches its max value for SFO/3(CoTmTb) NCs. Microwave properties of the SFO/x(CoTmTb) NCs were measured in the frequency range 33–50 GHz. From measured S11 and S21 parameters the main electrodynamic characteristics – permittivity and permeability (real and imaginary parts) were computed. © 2021 The Author(s)This work was financially supported by the Deanship for Scientific Research (Project application No. 2020-164-IRMC) of Imam Abdulrahman Bin Faisal University (IAU ? Saudi Arabia). Microwave characterization was partially supported by the Russian Science Foundation (Agreement No. 19-72-10071 from 06 Aug. 2019)

Influence of phase diagrams of the orientation slot-hole radiators on the orientation diagram turnstile the slot-hole aerial

Клыгач Денис Сергеевич - аспирант ЮУрГУ; [email protected]. Klygach Denis Sergeevich - postgraduate student of SUSU; [email protected]. Войтович Николай Иванович - д-р техн. наук, профессор, заведующий кафедрой конструирования и производства радиоаппаратуры ЮУрГУ; [email protected]. Voitovich Nikolay Ivanovich - PhD, professor, head of the Electronics design department of SUSU; [email protected]Рассматривается влияние фазовых диаграмм направленности щелевых излучателей на поведение диаграмм направленности (ДН) турникетной щелевой антенны. Приведены амплитудные и фазовые ДН щелевого излучателя и турникетной антенны. Проведено сравнение амплитудных ДН турникетной антенны, вычисленных без учета и с учётом фазовых ДН щелевых излучателей. Показано, что с ростом отношения ширины ленты к длине волны растёт угол разворота максимумов ДН относительно исходного положения, наблюдаемого при стремлении упомянутого отношения к нулю. In article influence of phase diagrams of an orientation of slot-hoie radiators on behavior of diagrams of an orientation (DO) turnstile the slot-hole aerial is considered. Are resulted peak and phase DO a slot-hole radiator and turnstile antenna. Comparison peak DO turnstile antenna, calculated without taking into account and taking into account phase DO slot-hole radiators is spent. It is shown that with growth of the relation of width of a tape to length of a wave the corner of a turn of maxima DO concerning the starting position observed at aspiration of the mentioned relation to zero grows

Optimization method for geometry of mirror antennas with special pattern

Клыгач Денис Сергеевич – аспирант кафедры конструирования и производства радиоаппаратуры, Южно-Уральский государственный университет; [email protected] Хашимов Амур Бариевич – канд. физ.-мат. наук, доцент кафедры конструирования и производства радиоаппаратуры, Южно-Уральский государственный университет; [email protected]. Klygach Denis Sergeevich – Post-Graduate Student of Radio Equipment Design and Production Department, South Ural State University; [email protected] Khashimov Amur Barievich – Candidate of Science (Physics and Mathematics), Associate Professor of Radio Equipment Design and Production Department, South Ural State University; [email protected]Предложен метод оптимизации геометрии рефлектора зеркальной антенны двойной кривизны. Рассматривается формирование косекансной диаграммы направленности в полосе частот, определяемой свойствами облучателя. Математическая модель зеркальной антенны основана на использовании методов геометрической оптики. Использование вычислительных методов повышенной точности позволяет существенно ускорить предложенный метод последовательных приближений. This paper proposes the optimization method for geometry of the double curvature reflector of mirror antenna. The forming of the cosecant pattern for given frequency range, which is determined by irraditor properties, is considered. Mathematical model of the mirror antenna is based on the methods of geometrical optics. The usage of computational methods of high accuracy allows to accelerate the proposed method of successive approximation