scholarly journals Influence of aluminum substitution on the fi eld of effective magnetic anisotropy and the degree of magnetic texture of anisotropic polycrystalline hexagonal ferrites of barium and strontium for substrates of microstrip devices of microwave electronics

2019 ◽  
Vol 21 (3) ◽  
pp. 166-174
Author(s):  
S. V. Shcherbakov ◽  
A. G. Nalogin ◽  
V. G. Kostishin ◽  
A. A. Alekseev ◽  
E. A. Belokon ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Anisotropy Field ◽  
Ceramic Technology ◽  
Preparation Technology ◽  
Magnetic Texture ◽  
Strontium Hexaferrites ◽  
Barium Hexaferrites ◽  
Microwave Electronics ◽  
Effective Magnetic Anisotropy ◽  
First Time

Abstract. In this paper, the effect of Al3+ ions substitutions on the value of the effective magnetic anisotropy field НАeff and the degree of magnetic texture f of the anisotropic polycrystalline hexagonal barium and strontium ferrites were studied. The samples were obtained by the ceramic technology method and the texture was formed by pressing in a magnetic field. The sample preparation technology presented in detail. The batches of barium hexaferrites were synthesized with the concentration of Al3+ ions: 0.9; 1.4; 2.5 and 2.6 formula units while strontium hexaferrites had Al3+ concentration of 0.1 formula units. It has been shown that by this technology barium and strontium hexaferrites with high value of (in range of 19—35 kOe) and with f = 80—83% could be obtained. The achieved values of НАeff and f could be sufficient for the production of substrates for microstrip microwave devices in millimeter−wave region.For the first time a raise in the degree of magnetic texture of polycrystalline barium hexaferrites with an increase of concentration of Al3+ ions were detected; a slight (5.5—5.8%) magnetic texture of isotropic strontium hexaferrites was also detected. The achieved results discussed in detail. For studied hexaferrites the mechanism of magnetic texture formation during the process of synthesis is proposed.

scholarly journals Measurement of effective magnetic anisotropy field and ferromagnetic resonance bandwidth at ferromagnetic resonance frequency in magnetically uniaxial hexagonal ferrites

2019 ◽  
Vol 5 (1) ◽  
pp. 33-39
Author(s):  
Alexey S. Semenov ◽  
Aleksey G. Nalogin ◽  
Sergey V. Shcherbakov ◽  
Alexander V. Myasnikov ◽  
Igor M. Isaev ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Ferromagnetic Resonance ◽  
Transmission Lines ◽  
Anisotropy Field ◽  
Nominal Composition ◽  
Hexagonal Ferrites ◽  
Magnetic Texture ◽  
Measurement Results ◽  
Effective Magnetic Anisotropy ◽  
Ferromagnetic Resonance Frequency

In this work we have considered metrological problems and measurement of magnetic parameters and presented methods of measuring effective magnetic anisotropy field HAeff and ferromagnetic resonance bandwidth ∆H in magnetically uniaxial hexagonal ferrites in the electromagnetic microwave working frequency range. The methods allow measuring HAeff in the 10–23 and 28–40 kE ranges and ∆H in the 0.5–5.0 range. One method (suitable for wavelength measurements in free space in the 3-mm wavelength range) has been implemented for the 78.33–118.1 GHz range. The other method (based on the use of microstrip transmission lines) has been implemented for the 25–67 GHz range. The methods have been tested for polycrystalline specimens of hexagonal barium and strontium ferrites with nominal composition or complex substituted and having high magnetic texture. The measurement results have been compared with those obtained using conventional measurement methods and spherical specimens. Our methods prove to be highly accurate and reliable.

scholarly journals Температурная зависимость эффективного поля магнитной анизотропии и ширины линии ферромагнитного резонанса поликристаллических сложнозамещенных гексагональных магнитноодноосных ферритов в диапазоне частот 25-67 GHz

2020 ◽  
Vol 90 (5) ◽  
pp. 782
Author(s):  
С.В. Щербаков ◽  
А.Г. Налогин ◽  
В.Г. Костишин ◽  
А.С. Семенов ◽  
Н.Е. Адиатулина ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Ferromagnetic Resonance ◽  
Barium Hexaferrite ◽  
Anisotropy Field ◽  
Ceramic Technology ◽  
Strontium Hexaferrite ◽  
Temperature Changes ◽  
Temperature Range ◽  
Resonance Linewidth ◽  
Ferromagnetic Resonance Linewidth

In the work in the frequency range 25 – 67 GHz the temperature changes of the effective magnetic anisotropy field and ferromagnetic resonance linewidth of the samples isotropic and anisotropic hexaferrite SrFe11.2Al0.1Si0.15Ca0.15O19 and anisotropic hexaferrite BaFe10.4Al1.4Si0.15Mn0.1O19 were studied. The samples obtained by ceramic technology with the pressing of the raw blanks in a magnetic field of 10 kOe. The studies were carried out in the temperature range+25 – +85 ºC. It was found that in the specified temperature range, the change in magnetic anisotropy is 9.8 Oe/ºC for barium hexaferrite and 4.2 Oe/ºC for strontium hexaferrite, and the change in ferromagnetic resonance linewidth is 12.2 Oe/ºC for barium hexaferrite and 10 – 12.3 Oe/ºC for strontium hexaferrite.

scholarly journals Влияние технологии получения ферритизированного порошка на степень магнитной текстуры пластин гексаферритов BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- и SrFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=-

2019 ◽  
Vol 45 (8) ◽  
pp. 34
Author(s):  
А.В. Тимофеев ◽  
В.Г. Костишин ◽  
Д.Н. Читанов
Keyword(s):  
Magnetic Field ◽  
Ceramic Technology ◽  
Magnetic Texture ◽  
Strontium Hexaferrites ◽  
Chemical Coprecipitation ◽  
The Magnetic Field ◽  
Ferritized Powder

The paper studies influence of the technology producing ferritized powder of barium and strontium hexaferrites on the degree of magnetic texture of plates based on them. It is shown that the use of chemical coprecipitation technology compared to ceramic technology allows to obtain hexaferrite plates with the same values of the magnetic field pressing of raw blanks, the degree of magnetic texture is 19 – 22 % higher.

Effect of Thickness on Mechanically Tunable Magnetic Anisotropy of FeGa Thin Films Deposited on Flexible Substrates

2015 ◽  
Vol 815 ◽  
pp. 227-232 ◽  
Author(s):  
Ying Yu ◽  
Shu Hong Xie ◽  
Qing Feng Zhan
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Effective Strain ◽  
Anisotropy Field ◽  
Saturation Field ◽  
Effective Anisotropy ◽  
Magnetostriction Constant ◽  
The Difference ◽  
Different Strains

A practical way to manipulate the magnetic anisotropy of magnetostrictive FeGa thin films grown on flexible polyethylene terephthalate (PET) substrates is introduced in this study. The effect of film thickness on magnetic properties and magnetostriction constant of polycrystalline FeGa thin films was investigated. The anisotropy field Hk of flexible FeGa films, i.e., the saturation field determined by fitting the hysteresis curves measured along the hard axis, was enhanced with increasing the tensile strain applied along the easy axis of the thin films, but this enhancement via strain became unconspicuous with increasing the thickness of FeGa films. In order to study the magnetic sensitivity of thin films responding to the external stress, we applied different strains on these films and measure the corresponding anisotropy field. Moreover, the effective magnetostriction constant of FeGa films was calculated from the changes of both anisotropy field and external strain based on the Villari effect. A Neel’s phenomenological model was developed to illustrate that the effective anisotropy field of FeGa thin films was contributed from both the constant volume term and the inverse thickness dependent surface term. Therefore, the magnetic properties for the volume and surface of FeGa thin films were different, which has been verified in this work by using vibrating sample magnetometer (VSM) and magneto-optic Kerr effect (MOKE) system. The anisotropy field contributed by the surface of FeGa film and obtained by MOKE is smaller than that contributed by the film volume and measured by VSM. We ascribed the difference in Hk to the relaxation of the effective strain applied on the films with increasing the thickness of films.

Exchange Bias in CrO2/Cr2O3 Bilayer Thin Films

2006 ◽  
Vol 45 ◽  
pp. 2528-2533 ◽  
Author(s):  
S. Srinath ◽  
N.A. Frey ◽  
H. Srikanth ◽  
G.X. Miao ◽  
A. Gupta
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Variable Thickness ◽  
Exchange Bias ◽  
Exchange Coupling ◽  
Hysteresis Loops ◽  
Anisotropy Constant ◽  
Effective Magnetic Anisotropy ◽  
Large Anisotropy

We have investigated the exchange bias in CVD grown epitaxial CrO2/Cr2O3 bilayer thin films using hysteresis loops and resonant RF transverse susceptibility. M-H loops indicated an enhanced coercivity without appreciable loop shift and the transverse susceptibility in CrO2/Cr2O3 bilayers revealed features associated with both the ferromagnetic and antiferromagnetic phases. In addition, TS yielded large anisotropy constant (Keff) values depending on the fraction of Cr2O3 present. The large anisotropy fields observed cannot be accounted for by the variable thickness of CrO2 alone and are indicative of possible exchange coupling between CrO2 and Cr2O3 phases that significantly affects the effective magnetic anisotropy.

‘We must send you a sample’—a Persian–European dialogue: insights into late nineteenth-century ceramic technology based on chemical analysis of tiles from the Ettehadieh house complex, Tehran, Iran

2020 ◽  
Author(s):  
Moujan Matin ◽  
Mohammad Gholamnejad ◽  
Ali Nemati Abkenar
Keyword(s):  
Nineteenth Century ◽  
Chemical Analysis ◽  
Production Technology ◽  
Chemical Study ◽  
Ceramic Technology ◽  
Late Nineteenth Century ◽  
Chemical Analyses ◽  
Technological Information ◽  
Late Nineteenth ◽  
First Time

This paper focuses on the production technology of late nineteenth-century tiles from the Ettehadieh House Complex in Tehran, Iran. It makes use of the opportunity to provide for the first time the results of chemical and microstructural analyses of late nineteenth-century tiles selected directly from context and with known provenance. The paper integrates the results of chemical study of the Ettehadieh tiles with other available technological information on nineteenth-century Persian tiles, including chemical analyses of signed tiles and samples of pigments, as well as the study of the treatise of a certain Persian potter, ‘Ali Mohammad Isfahani, to suggest processes of materials procurement and manufacture. These processes are used as evidence to discuss trade and technological interactions between Iran and Europe in the nineteenth century.

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