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1

Effects of variable fluid properties and mixed convection on biomagnetic fluid flow and heat transfer over a stretching sheet in the presence of magnetic dipole

Murtaza M. G., Alam Jahangir, Tzirtzilakis E. E., Shamshuddin Md., Ferdows M.

Journal of Power Technologies

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2023

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Vol. 103, nr 4

193--208

EN

This investigations covers the numerical analysis of a steady biomagnetic fluid flow (BFD) that passed through a two dimensional stretching sheet under the influence of magnetic dipole. The effect of fluid variable viscosity and thermal conductivity are also taken into consideration as assumed to vary as linear function of temperature. Our model mathematically formulated for BFD namely blood which consist of principles of magnetohydrodynamic (MHD) and ferrohydrodynamic (FHD), where blood treated as an electrically conducting fluid as well as polarization. Using similarity transformations, the governing system of partial differential equations are transferred into system of ordinary differential equations (ODE). The resulting coupled non linear ODE is numerically solved by employing bvp4c function technique available in MATLAB software. The effects of pertinent parameters namely ferromagnetic interaction parameter, magnetic field parameter, mixed convection parameter, viscosity variation parameter, Prandtl number, thermal conductivity parameter etc are plotted and discussed adequately for velocity and temperature profile as well as skin friction coefficient and rate of heat transfer. The results revels that velocity profile decreases as enhanced values of ferromagnetic number whereas temperature profile increased. Also found that skin friction coefficient reduces and rate of heat transfer increases by increasing values of thermal conductivity parameter and viscosity variation parameter. For numerical validation a comparisons has been made for some specific values with previous investigators. We hope that the present analysis will present in bio-medical and bio-engineering sciences.

2

Magnetostrictive Functional Materials of Tb0.27Dy0.73(Fe1-xAlx)2 Series as Prospective Constituents of Magnetoelectric Composites

Winiarska Barbara, Guzdek Piotr, Kuciakowski Juliusz, Tokarz Waldemar, Sikora Marcin, Pszczoła Jarosław

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

215--222

EN

Structural, magnetic, and magnetostrictive properties of two-sublattice Tb0.27Dy0.73(Fe1-xAlx)2 polycrystalline intermetallic ferrimagnets (x = 0-0.2 and 1.0) were studied using X-ray powder diffraction, magnetometry, and strain gauge magnetostriction measurements. Temperature dependences of magnetization starting from 80 K were presented, and Curie temperatures were estimated. Coercive force, residual, and saturation magnetizations were determined from the magnetic hysteresis loops at room temperature. Longitudinal, transversal, form and volume magnetostrictions were investigated against the x parameter and the intensity of the magnetic field. The piezomagnetic coefficients were determined and the maximum value at the field below 1 kOe, even enhanced than that in Terfenol-D, was observed for the material TTb0.27Dy0.73(Fe0.9Al0.1)2. It means that this compound is promising for use in magnetoelectric composites.

3

Single sheet tester for measuring core losses with novel adaptive algorithm of waveform

Lerch Tomasz, Rad Michał, Rams Witold

Archives of Electrical Engineering

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2022

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Vol. 71, nr 4

851--864

EN

This paper presents a novel method of waveform generation in a single-sheet tester (SST) for measuring core losses and permeability in a steel sheet. Some improvements and modifications of the apparatus are also described. The improved way of working of a SST is important, especially in the extended range of polarization (up to 1.9 T). The system consists of hardware and software. Everything together was tested and has given good results. The proposed algorithm is described and compared to previously known methods.

4

Effect of magnetic field on thermosolutal instability of rotating ferromagnetic fluid under varying gravity field

Pundir S. K., Nadian P. K., Pundir R.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 1

201--214

EN

This paper deals with the theoretical investigation of the effect of a magnetic field, rotation and magnetization on a ferromagnetic fluid under varying gravity field. To find the exact solution for a ferromagnetic fluid layer contained between two free boundaries, we have used a linear stability analysis and normal mode analysis method. For the case of stationary convection, a stable solute gradient has a stabilizing effect, while rotation has a stabilizing effect if 0λ > and destabilizing effect if 0λ < . Further, the magnetic field is discovered to have both a stabilizing and destabilizing effect for both 0λ > and 0λ < . It is likewise discovered that magnetization has a stabilizing effect for both 0λ > and 0λ < in the absence of the stable solute gradient. Graphs have been plotted by giving numerical values of various parameters. In the absence of rotation, magnetic field and stable solute gradient, the principle of exchange of stabilities is found to hold true for certain conditions.

5

The influence of self-doping of stibnite ore with impurities on the preparation, heat capacity, magnetic and transport properties of tetrahedrite Cu12Sb4S13

Chen Yuqi, Li Liang, Zhang Qianjun, Zhang Congzheng, Hirai Shinji

Materials Science Poland

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2020

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Vol. 38, No. 3

484-492

EN

Stibnite mineral (mainly Sb2S3) has been employed for the synthesis of tetrahedrite Cu12Sb4S13 bulk material by spark plasma sintering. High purity Cu12Sb4S13 can be quickly obtained by two sintering procedures at temperatures from the range of 420 °C to 440 °C for 1 h. Appropriate reduction of Cu content (Cu12+xSb4S13, x ⩽ –0.05) or CuS content (Cu12−ySb4S13−y, y = 0.1 or 0.3) was beneficial to fabricate Cu12Sb4S13. The secondary resintering improved the purity of Cu12Sb4S13 material. The first-order magnetic phase transformation with magnetic hysteresis effect was confirmed by the behavior of susceptibility, heat capacity and resistivity. The magnetization showed a linear increase with increasing field (up to 7 T) and non-saturation behavior was observed. The impurities in stibnite mineral Sb2S3 had a weak influence on the transformation temperature but affected the low-temperature magnetization value (~0.15, close to natural tetrahedrite). Similar transformation was observed by the analysis of heat capacity. The properties such as electrical resistivity, Seebeck coefficient and thermal conductivity were also measured for Cu11.9Sb4S13 and Cu11.9Sb4S12.9. The maximum figure of merit ZT of Cu11.9Sb4S12.9 was 0.22 at 367 K.

6

Structural and magnetic properties of gadolinium modified BiFeO3

Ramirez Guzmán L. M., Cruz Pacheco A. F., Gómez Cuaspud J. A., Parra Vargas C. A.

Materials Science Poland

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2020

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Vol. 38, No. 4

559--565

EN

This paper reports the synthesis and characterization of the Bi0.94Gd0.06FeO3 sample obtained by solid state reaction method. The structural and morphological analysis was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Rietveld refinement analysis, confirming the obtaining of a rhombohedral crystalline phase and R3c space group (a = b = 5.577 Å and c = 13.847 Å), with an interconnected structure. Studies by X-ray photoelectron spectroscopy (XPS) revealed trivalent oxidation states of Bi, Fe and Gd ions. The synthesized sample exhibited a non-linear M–H loop indicating a weak ferromagnetic behavior with a remnant magnetization of 6.34 emu∙mol−1 and a coercive field of 295 Oe. The obtained structural and magnetic characteristics make these materials of great interest as multiferroic components.

7

Electromagnetic system for improving the adhesion of wheels to rails

Osenin Yurij, Antoshkina Lidiya, Sosnov Igor, Shapran Evgeniy, Chesnokov Aleksei

Transport Problems

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2019

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T. 14, z. 1

59--67

EN

The article describes the design of a system used for the improvement of the adhesion of locomotive wheels to rails; the principle of which is based on the electromagnetic feeding of the contact area with the bulk material that has magnetic properties and high hardness (iron scale Fe3O4 and magnetite FeO×Fe2O3). The experimental results of laboratory and bench tests confirming the effectiveness of the proposed system compared with the existing devices using quartz sand to improve the adhesion of wheels to rails are presented. It is concluded that the use of an electromagnetic system for improving the particle supply to the wheel/rail interface is promising.

8

Structural and magnetic studies on Co-Zn nanoferrite synthesized via sol-gel and combustion methods

Vara Prasad B. B. V. S., Ramesh K. V., Srinivas A.

Materials Science Poland

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2019

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Vol. 37, No. 1

39--54

EN

Co–Zn nanocrystalline ferrites with chemical composition Co0.5Zn0.5 Fe2O4 were synthesized by sol-gel and combustion methods. The sol-gel method was carried out in two ways, i.e. based on chelating agents PVA and PEG of high and low molecular weights. In auto-combustion method, the ratio of citric acid to metal nitrate was taken as 1:1, while in sol-gel method the chelating agents were taken based on oxygen balance. All the three samples were studied by thermogravimetric and differential thermal analysis for the identification of phase formation and ferritization temperature. The synthesized samples were characterized by powder X-ray diffraction and FT-IR spectroscopy without any thermal treatment. The measured lattice constants and observed characteristic IR absorption bands of the three samples are in good agreement with the reported values showing the formation of a cubic spinel structure. The crystallite sizes of all samples were determined using high intensity peaks and W-H plot. Size-Strain Plot method was also implemented since two of the samples showed low crystallite sizes. The least crystallite size (5.5 nm) was observed for the sample CZVP while the highest (23.8 nm) was observed for the sample CZCA. Cation distribution was proposed based on calculated and observed intensity ratios of selected planes from X ray diffraction data. All structural parameters were presented using experimental lattice constant and oxygen positional parameter, and they correlated with FT-IR results. Magnetic measurements were carried out using vibrating sample magnetometer at room temperature to obtain the characteristic parameters such as saturation magnetization, coercivity, remanence, squareness ratio and Bohr magnetons. Among all, the sample synthesized via citric acid autocombustion method displayed a remarkably higher magnetization of 53 emu/g and the remaining two samples displayed low magnetization values owing to their smaller crystallite sizes.

9

The influence of pulsating tensile stress on residual magnetic field of P91 steel samples

Złocki A., Roskosz M., Kwaśniewski J.

Advances in Materials Science

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2019

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Vol. 19, nr 2(60)

72--82

EN

Measurements of Residual Magnetic Field RMF (the tangential component parallel to the load direction) were taken on the surface of P91 steel plate samples (X10CrMoVNb9-1) subjected to periodic pulsating tensile cyclic loads with the use of flux-gate and magnetoimpedance sensors, and preliminary measurement results are compiled and analyzed. The study investigates how the microstructure and load cycle parameters affect the RMF changes due to stress variations. Each combination of parameters: microstructure and load cycle corresponds to the characteristic variability pattern of magnetization and its maximum and minimum values.

10

Magnetoresistance effect in layered cobaltite Sr0.9Y0.1CoO2.63

Bushinsky M., Tereshko N., Mantytskaya O., Fedotova V., Lanovsky R.

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

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2018

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Nr 13

105--114

EN

The structure and the magnetic and magnetotransport properties of the perovskite sample Sr0.9Y0.1CoO2.63 have been studied using different diffraction methods and magnetization and conductivity measurements. Synchrotron X-ray diffraction shows that the sample is structurally two-phase. The majority phase has a tetragonally distorted unit cell and is described by the space group I4/mmm. A very strongly broadened superstructure peak observed at small angles in X-ray diffraction patterns at temperatures below 400 K are explained by the existence of a monoclinic phase with large unit cell whose phase fraction is much smaller than that of the tetragonal phase, but which is dominant in the sample Sr0.8Y0.2CoO2.65. The spontaneous magnetization strongly increases with increasing the Y content up to 20% due to formation of the monoclinic phase. The magnetic structure is predominantly antiferromagnetic G-type with magnetic moments 1.5 μB in the layers of CoO6 octahedra and 2 μB in the anion-deficient CoO4+γ layers. The electrical conductivity of the sample Sr0.9Y0.1CoO2.63 has semiconducting character. The magnetoresistance reaches 58% for the field B = 14 T at 5 K and decreases strongly with the increasing temperature and Y content.

PL

Struktura i właściwości magnetyczne i magnetotransportowe perowskitu Sr0.9Y0.1CoO2.63 zostały zbadane przy użyciu różnych metod dyfrakcyjnych oraz pomiarów namagnesowania i przewodnictwa. Dyfrakcja rentgenowska mierzona na synchrotronie pokazuje, że próbka ma strukturę dwufazową. Główna faza ma tetragonalnie zniekształconą komórkę elementarną i jest opisana przez grupę przestrzenną I4 /mmm. Pik o bardzo mocno poszerzonej superstrukturze obserwowano pod niewielkimi kątami w dyfraktogramach rentgenowskich w temperaturach poniżej 400 K i jest związany z istnieniem fazy monoklinowej o dużej komórce elementarnej, której frakcja fazowa jest znacznie mniejsza niż faza tetragonalna, ale która jest dominujący w próbce Sr0.8Y0.2CoO2.65. Spontaniczne namagnesowanie silnie wzrasta wraz ze wzrostem zawartości Y do 20% z powodu tworzenia się fazy monoklinowej.

11

Magnetic Properties of Steel Ball Samples, Investigated before and after Nitriding

Fuks H., Kaczmarek S. M., Leniec G., Michalski J., Kucharska B., Wach P.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1235--1242

EN

Group of steel balls with different chemical composition, diameters and nitriding treatment parameters were investigated with using magnetic resonance and magnetization methods. Emerging nitrided regions consists of diffusion and surface layer of iron nitrides. The thickness of the individual layers depends on the type of steel and process parameters. Resonance signal shape and position were successfully described in the ferromagnetic resonance regime expected for dense iron magnetic system. Influence of the sample size, thermal treatment and carbon content on the absorption signal has been analyzed. Significant magnetic anisotropy has been revealed, as well as non-usual increasing of the magnetization as a function of temperature. It suggests, that overall antiferromagnetic ordering, destroyed by thermal movement, lead to increasing of the ferromagnetic region.

12

Magnetotransport and magnetic properties of manganites doped with iron and aluminum

Troyanchuk I., Bushinsky M., Tereshko N., Fedotova V.

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

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2017

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Nr 11

5--10

EN

The single crystals of La0.7Ba0.3(Mn1-xFex)O3 (x ≤ 0.28) and La0.7Ba0.3(Mn1-xAlx)O3 (x ≤ 0.15) compositions were grown using flux method and characterized by X-ray, electrical and magnetization measurements. The replacement of Mn ions by Al ions in the La0.7Ba0.3Mn1-xAlxO3 system leads to a decrease in the temperature to 311 K for the sample x=0.1. The Fe-doping above x=0.2 destroys a long range ferromagnetic order thus leading to a spin glass state. It is found that insulating spin glasses exhibit a large magnetoresistance in the paramagnetic region that is comparable to that for ferromagnetic crystals showing metal–insulator transition near TC.

PL

Monokryształy La0,7Ba0,3(Mn1-xFex)O3 (x ≤ 0,28) i La 0,7Ba 0,3 (Mn1-xAlx)O3 (x ≤ 0,15) wyhodowano metodą strumieniową i charakteryzowano poprzez badania rentgenowskie, pomiary elektryczne i magnetyzacyjne. Zastąpienie jonów Mn jonami Al w układzie La0,7Ba0,3Mn1-xAlxO3 prowadzi do obniżenia temperatury do 311 K dla próbki x = 0,1. Domieszka Fe powyżej x = 0,2 niszczy ferromagnetyczny porządek dalekiego zasięgu atomów Fe, prowadząc w ten sposób do spinowego stanu typu szkła. Stwierdzono, że izolacyjny spinowy stan typu szkła wykazuje dużą rezystancję magnetyczną w obszarze paramagnetycznym, która jest porównywalna z kryształami ferromagnetycznymi i wykazują przejście metal-izolator w pobliżu TC.

13

Synthesis of Cu and Ce co-doped ZnO nanoparticles: crystallographic, optical, molecular, morphological and magnetic studies

Rawat M., Singh J., Singh J., Singh C., Singh A., Kukkar D., Kumar S.

Materials Science Poland

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2017

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Vol. 35, No. 2

427--434

EN

In the present research work, crystallographic, optical, molecular, morphological and magnetic properties of Zn1-xCuxO (ZnCu) and Zn1-x-yCeyCuxO (ZnCeCu) nanoparticles have been investigated. Polyvinyl alcohol (PVA) coated ZnCu and ZnCeCu nanoparticles have been synthesized by chemical sol-gel method and thoroughly studied using various characterization techniques. X-ray diffraction pattern indicates the wurtzite structure of the synthesized ZnCu and ZnCeCu particles. Transmission electron microscopy analysis shows that the synthesized ZnCu and ZnCeCu particles are of spherical shape, having average sizes of 27 nm and 23 nm, respectively. The incorporation of Cu and Ce in the ZnO lattice has been confirmed through Fourier transform infrared spectroscopy. Room temperature photoluminescence spectra of the ZnO doped with Cu and co-doped Ce display two emission bands, predominant ultra-violet near-band edge emission at 409.9 nm (3 eV) and a weak green-yellow emission at 432.65 nm (2.27 eV). Room temperature magnetic study confirms the diamagnetic behavior of ZnCu and ferromagnetic behavior of ZnCeCu.

14

A way of neodymium-iron-boron magnets regeneration in surface-mounted PMSM used in electric vehicles

Łebkowski A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 5

751--758

EN

The paper describes an efficient method of magnetization of permanent magnets, mounted on synchronous and BLDC motor rotors, which employs an air coil. A developed mathematical model of an electromagnetic circuit is presented, which was simulated in an ANSYS-MAXWELL environment. The performed simulations and experimental tests allowed optimization of the physical process of magnetization of permanent magnets mounted on an electrical machine rotor. The adopted method allowed achieving more favourable conditions of magnetization – less financial expenditure allowed to achieve the same results.

15

Magnetic studies of 0.7(Fe2O3)/0.3(ZnO) nanocomposites in nanopowder form and dispersed in polymer matrix

Typek J., Wardal K., Zolnierkiewicz G., Szymczyk A., Guskos N., Narkiewicz U., Piesowicz E.

Materials Science Poland

|

2016

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Vol. 34, No. 2

286--296

EN

Magnetic properties of 0.7(Fe2O3)/0.3(ZnO) nanocomposite synthesized by traditional wet chemistry method and containing only two phases: ZnO (nonmagnetic) and Zn Fe2O4 (magnetic, with nanocrystallites of average size 12 nm, but forming large agglomerates, up to 100 nm in size) were studied by DC magnetization and ferromagnetic resonance (FMR). The investigated nanocomposite was either in a form of nanopowder or dispersed at concentration of 0.1 wt.% in poly(ethylene naphthalate-block-tetramethylene oxide) PTMO-b-PEN polymer matrix. Similarities and differences in magnetic behavior of these two samples revealed by the study of static magnetization and FMR spectra have been discussed relative to different morphologies and the associated variation of interparticle interactions. Moreover, thermal and thermo-oxidative stability of the nanocomposite and the neat polymer have been studied by thermogravimetric method.

16

Magnetic and magnetotransport properties of La0.5Sr0.5Co0.8Me0.2O3 (Me=Cr, Fe) cobaltites

Troyanchuk I., Bushinsky M., Tereshko N., Fedotova V.

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

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2015

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Nr 8

69--76

EN

Magnetic and magnetotransport properties of La0.5Sr0.5Co0.8Me0.2O3 (Me = Cr, Fe) stoichiometric cobaltites has been investigated in magnetic fields up to 14 T. It is shown that doping with Fe ions changes spontaneous magnetization only slightly herewith the Curie point significantly decreases. The chromium doping leads to dramatic decrease of magnetization and the Curie point and a strong increase in magnetoresistance at low temperature. The obtained results indicate that the magnetic interactions between Co and Fe are positive whereas those between Co and Cr ions are negative. Enhancement of magnetoresistance is attributed to the magnetic field induced transition from antiferromagnetic order to ferromagnetic one.

PL

Właściwości magnetyczne i magnetotransportowe stoichiometrycznych kobaltytów zbadano w polach magnetycznych do 14T. Ustalono, że domieszkowanie przez jony Fe zmienia namagnesowanie spontaniczne bardzo słabo w tym czasie jak punkt Curie obniża się znacząco. Domieszkowanie przez atomy chromu powoduje dramatyczne zmniejszenie namagnesowania i obniżenie punktu Curie i mocny wzrost magneto rezystancji w niskich temperaturach. Otrzymane rezultaty wskazują oddziaływanie magnetyczne pomiędzy Co i Fe jest pozytywne w tym czasie jak pomiędzy Co a Cr jest negatywne. Wzmocnienie magnetorezystancji przypisano do pola magnetycznego indukowanego przejściem z antyferromagnetycznego układu do ferromagnetycznego.

17

Comparative Analysis of Magnetic Field in Surface Permanent Magnet Motor at Various Types of Rotor Magnetization

Petkovska L., Cvetkovski G.

Przegląd Elektrotechniczny

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2015

|

R. 91, nr 12

189-192

EN

In this paper the influence of magnetization pattern on the magnetic field features and characteristics in a surface mounted permanent magnet motor is analysed. A comparative analysis of performance characteristics for a conventional surface PM motor with Halbach array topologies is presented. The study is based on FEM field computations that enable the visibility of the magnetic properties and characteristics. The emphasis is put on electromagnetic field distribution, magnetic flux per pole profile and components of the flux density in the air gap.

PL

W artykule przeprowadzono analizę wpływu sposobu magnetyzacji na właściwości pola magnetycznego I charakterystyki w silniku z powierzchniowym magnesem trwałym. Przedstawiona została analiza porównawcza charakterystyki działania dla konwencjonalnego silnika z powierzchniowym magnesem trwałym w układzie Halbacha. Badania zostały oparte na metodzie elementów skończonych, która umożliwia „widzenie” właściwości magnetycznych i charakterystyk. Nacisk położono na rozkład pola elektromagnetycznego, strumień magnetyczny w profilu i składowe indukcji magnetycznej w szczelinie powietrznej.

18

Structure and some magnetic properties of (BiFeO3)x-(BaTiO3)1-x solid solutions prepared by solid-state sintering

Kowal K., Kowalczyk M., Czekaj D., Jartych E.

Nukleonika

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2015

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Vol. 60, No. 1

81--85

EN

This paper presents the results of the study on structure and magnetic properties of the perovskite-type (BiFeO3)x-(BaTiO3)1-x solid solutions. The samples differing in the chemical composition (x = 0.9, 0.8, and 0.7) were produced according to the conventional solid-state sintering method from the mixture of powders. Moreover, three different variants of the fabrication process differing in the temperatures and soaking time were applied. The results of X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and vibrating sample magnetometry (VSM) were collected and compared for the set of the investigated materials. The structural transformation from rhombohedral to cubic symmetry was observed for the samples with x = 0.7. With increasing of BaTiO3 concentration Mössbauer spectra become broadened refl ecting various confi gurations of atoms around 57Fe probes. Moreover, gradual decreasing of the average hyperfi ne magnetic fi eld and macroscopic magnetization were observed with x decreasing.

19

Magnetoresistance peculiarities and magnetization of materials with two kinds of superconducting inclusions

Shevtsova O. N.

Materials Science Poland

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2015

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Vol. 33, No. 1

73--81

EN

Low-temperature properties of a crystal containing type I superconducting inclusions of two different materials have been studied. In the approximation assuming that the inclusions size is much smaller than the coherence length/penetration depth of the magnetic field, the theory of magnetoresistance of a crystal containing spherical superconducting inclusions of two different materials has been developed, and magnetization of crystals has been calculated. The obtained results can be used for correct explanation of the low temperature conductivity in binary and more complex semiconductors, in which precipitation of the superconducting phase is possible during the technological processing or under external impact.

20

Straty mocy w typowych blachach prądnicowych

Banach A., Mazgaj W., Rozegnał B.

Wiadomości Elektrotechniczne

|

2014

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R. 82, nr 12

24--26

PL

Przedstawiono stratność typowych blach prądnicowych i jej zależność od częstotliwości przemagnesowania oraz od maksymalnej wartości indukcji występującej w czasie procesu magnesowania.

EN

The paper presents lossiness of typical generator sheets and its dependence on magnetization frequency and maximum value of induction that occurs during magnetization process.