Annotation of the results obtained in 2023
During the reporting period, the following work was carried out: 1. Ferrites with a cubic structure Ni1-xZnxFe2O4 (x = 0.0; 0.1; 0.2; 0.3; 0.4) were synthesized using a short technological scheme using ceramic technology. Their phase composition, structure and magnetic properties have been studied. 2. Composite materials based on Ni1-xZnxFe2O4 ferrites have been developed. The electromagnetic properties (spectra of complex permeability and permittivity, and reflection coefficients) of composites were studied in the frequency range from 0.01 to 18 GHz. 3. Composites based on ferrites Ba3Co1,9Ti0,4Fe23,7O41 and Ba2NiCuFe12O22 were developed using the magnetic texturing method. The electromagnetic properties of composites were studied in the frequency range from 0.01 to 18 GHz, and their dependence on the influence of a constant magnetic field during their polymerization was determined. 4. The structural characteristics of the manufactured composite materials were studied: distribution of filler particles, type of magnetic texture. 5. The degree of magnetic texture of composites when exposed to magnetic fields of different strengths was calculated. 6. Multilayer composites based on hexaferrites Ba3Co1,9Ti0,4Fe23,7O41 and Ni0.7Zn0,3Fe2O4 were manufactured. Their electromagnetic properties were studied in the frequency range from 0.01 to 18 GHz. 7. A methodology has been compiled for the production of magnetic polymer composite materials based on oxide ferrimagnetic powders for their use in solving problems of electromagnetic compatibility. Scientific results obtained: 1. Ceramic technology using a short technological scheme (without pre-firing) can be used to obtain single-phase nickel-zinc ferrites with high saturation magnetization values. Wet pressing and high pressure lead to a decrease in the porosity of the samples, which increases the completeness of chemical reactions and the rate of formation of the target phase in the synthesis products. Also, the dense packing of the initial raw contributes to the rapid growth of crystallites. A high synthesis temperature leads to an increase in saturation magnetization. Changing the concentration of zinc ions significantly affects the magnetic properties of the ferrites under study. Thus, by varying the chemical composition, it is possible to synthesize ferrites for the required operating temperature ranges with specified magnetic properties. 2. The influence of a constant magnetic field on composites made on the basis of hexaferrite powders with magnetic crystalline anisotropy of the “easy plane” type during their polymerization makes it possible to increase the values of the real and imaginary parts of the permeability and improve radio absorption properties without increasing the thickness of the absorber and without changing chemical composition. 3. Using magnetic fields of different strengths and fillers with different particle sizes, it is possible to select the required band and level of absorption of electromagnetic radiation by changing the values of complex permeability. 4. The influence of a constant magnetic field of 2.5 kOe on composites made on the basis of hexaferrite powders with magnetic crystalline anisotropy of the “easy plane” type during their polymerization makes it possible to achieve a uniform distribution of filler particles and a high degree of magnetic texture (at least 70%). 5. The use of multilayer structures consisting of ferrite powders with a cubic and hexagonal structure makes it possible to significantly increase the bandwidth and level of the absorption band of high-frequency electromagnetic radiation compared to single-layer composites of the same thickness 6. To create broadband absorbers, multilayer structures with layers of hexaferrites and spinel ferrites of various compositions with domain boundary resonance frequencies and natural ferromagnetic resonance in the long-wave part of the microwave range can be used.

 

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Annotation of the results obtained in 2022
During the reporting period, the following works were carried out: 1. The synthesis of oxide ferrimagnets with a hexagonal and cubic structure was carried out using standard ceramic technology, self-propagating high-temperature synthesis (SHS), the sol-gel method, and the mechanochemical method. 2. Studies of the structural characteristics and phase composition of the ferrites have been carried out. 3. Studies of the magnetic properties (saturation magnetization, remanent magnetization, coercive force, anisotropy field, ferromagnetic resonance method for hexaferrites, and according to the law of approach to saturation for ferrites with structural spinel) of the ferrite powders have been carried out. 4. The particle sizes of BaFe12O19 hexaferrites were determined from calculations of the coherent scattering region for all ferrite powder samples. 5. The temperature dependences of the initial permeability of the ferrite powders were measured. 6. The selection of a binder for the manufacture of samples of composite materials was carried out. 7. Samples of composite materials based on the ferrites were made. 8. Measurements of the reflection and transmission coefficients of composite materials were carried out. 9. The values of the initial permeability of samples of composite materials are determined. 10. The full spectra of the complex permeability have been reconstructed using the Kramers-Kronig relations. 11. The article was prepared and published the journal "Inventions". 12. The results of the work will be presented at the international conference "Uglerod: fundamentalnye problemy nauki, materialovedenie, tekhnologiya" (CFPMST 2023), June 7-9, 2023. The results obtained during the work: 1. BaFe12O19 hexaferrite samples synthesized according to a) standard ceramic technology, b) mechanochemical method, c) sol-gel method. 2. Samples of NiFe2O4 and CoFe2O4 ferrites with a spinel structure. 3. Samples of the system of Y-type hexaferrites Ba2Co2-xZnxFe12O22 (x = 0.0; 0.5; 1.0; 1.5), obtained by the method of self-propagating high-temperature synthesis without application of mechanical activation of powders of the initial oxides. 4. Samples of a system of Y-type hexaferrites Ba2Co2-xZnxFe12O22 (x = 0.0; 0.5; 1.0; 1.5) obtained by self-propagating high-temperature synthesis with application of preliminary mechanical activation of the initial oxides. 5. Samples of a system of Y-type hexaferrites Ba2Co2-xTixFe12O22 (x = 0,0; 0,5; 1,0; 1,5). 6. Samples of NiFe2O4 (S-type), Ba2NiCuFe12O22 (Y-type) and Ba3Co1,9Ti0,4Fe23,7O41 (Z-type) ferrites obtained by standard ceramic technology. 7. Hysteresis loops of the studied samples. 8. Pictures of scanning electron microscopy of the studied samples. 9. X-ray diffraction diagrams of the studied samples. 10. Samples of composite materials of the following compositions: a) 70 % wt Ba3Co1,9Ti0,4Fe23,7O41 + 30 % wt ED-20; b) 70 % wt NiFe2O4 + 30 % wt ED-20; c) 70 % wt BaFe12O19 + 30 % wt ED-20; d) 70 % wt Ba2CoZnFe12O22 + 30 % wt ED-20; e) 65 % wt + 34,95 % wt ED-20 + 0,5 % wt MWCNT; f) 75 % wt Ba2NiCuFe12O22 + 25 % wt ED-20. 11. Spectra of the real (μ') and imaginary (μ'') parts of the permeability; 12. Spectra of the real (ε') and imaginary (ε'') parts of the permittivity; 13. Initial values of the real and imaginary parts of the permeability and permittivity; 14. Reflection coefficient spectra of samples of composite materials. Links to information resources on the Internet dedicated to the project: Kompozity, sozdannye na RFF, budut luchshe pogloshchat' elektromagnitnoe izluchenie. ¬– URL: https://news.tsu.ru/news/v-tgu-sozdayut-materialy-sposobnye-pogloshchat-elektromagnitnoe-izluchenie/ (access date 04.05.2023)

 

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