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1.
Z. V. Golubenko A. S. Kamzin L. P. Ol’khovik M. M. Khvorov Z. I. Sizova V. P. Shabatin 《Physics of the Solid State》2002,44(9):1698-1702
Magnetization and remagnetization processes in a close-packed nanodispersed barium hexaferrite powder sample in the magnetically stable state were analyzed. Reversibility effects were discussed in terms of interparticle interaction. Judging from the magnetization curve and the parameters characterizing remagnetization irreversibility, the sample under study is a model system of small Stoner-Wohlfarth particles. 相似文献
2.
New trisubstituted biphthalonitrile/magnetite (TSB/Fe3O4) magnetic hybrid microspheres were synthesized from TSB and FeCl3 · 6H2O using the method of one-stage thermal temperature crystallization of solvents. The morphology and structure of magnetic hybrid microspheres were inspected using a scanning electron microscope, IR Fourier spectroscopy, and X-ray diffraction. It was found that the grown TSB/Fe3O4 magnetic hybrid microspheres represent spherical particles with an average size of ~137 nm and a small size spread. The size and size distribution of magnetic hybrid microspheres can be controlled by a small change in the ratio of TSB and Fe3+ ion contents in the microsphere. TSB/Fe3O4 hybrid microspheres exhibit a rather high saturation magnetization (58.16 emu g–1) and new microwave electromagnetic properties, i.e., lower (in comparison with published) dielectric losses at low frequencies; magnetic losses are increased obviously due to an increase in the TSB content. Furthermore, it is detected that magnetic hybrid microspheres absorb microwaves, and strong reflection losses in a wide frequency range are established. The effective reflection loss of–31 dB is obtained in the microwave range from 2 to 16 GHz due to TSB content variations. Wide absorption properties of microwaves along with regular spherical shape and excellent magnetic properties offer wide opportunities for various applications of TSB/Fe3O4 magnetic hybrid microspheres as functional materials. 相似文献
3.
Kamzin A. S. Valiullin A. A. Bingolbali A. Doǧan N. 《Physics of the Solid State》2020,62(7):1231-1239
Physics of the Solid State - Changes in the structure and properties of the Ni1 – xCuxFe2O4 ferrites-spinel magnetic nanoparticles depending on the Cu ion concentration (0... 相似文献
4.
Direct comparison of the properties of a thin surface layer and the bulk of macroscopic hematite (α-Fe2O3) crystals was used to study the magnetic structure of the surface layer and the bulk and the processes attendant on spin-reorientation phase transition (SRT). The investigation tool was simultaneous γ-ray, X-ray, and electronic Mössbauer spectroscopy, which enabled us to study the bulk and surface properties of macroscopic samples simultaneously and to compare them directly. Direct evidence of the existence of a surface “transition layer” on hematite crystals is obtained. The existence of this layer was suggested and described by Krinchik and Zubov [JETP 69, 707 (1975)]. The study in the SRT region showed that (1) the Morin SRT in the crystal bulk occurs in a jump (as a first-order phase transition), whereas in the surface layer of about 200 nm thick, some smoothness appears in the mechanism of magnetic-moment reorientation; (2) SRT in the surface layer, as in the bulk, involves an intermediate state in which low-and high-temperature phases coexist; and (3) SRT in the surface layer occurs at a temperature several degrees higher than in the bulk. Our experimental evidence on the SRT mechanism in the surface layer correlates with the inferences from phenomenological theory developed by Kaganov [JETP 79, 1544 (1980)]. 相似文献
5.
Kamzin A. S. Cao J. W. Wei F. L. Valiullin A. A. Zaripova L. D. 《Physics of the Solid State》2017,59(5):1027-1033
Physics of the Solid State - Magnetic L10–FePt(10 nm)/Fe(t, nm)/Ta(2 nm) (t is the Fe film thickness that is varied from 0 to 15 nm) multilayer structures have been prepared by magnetron... 相似文献
6.
A comparative analysis has been carried out of the physical-chemical state of the surface and bulk of single-crystal films of the iron garnet Y2.6Sm0.4Fe3.7Ga1.3O12 on substrates consisting of a gadolinium-gallium garnet single crystal. To carry out this study, we used the method of simultaneous γ-ray, x-ray, and electron Mösbauer spectroscopy, which made it possible to simultaneously extract information from the surface layers and the bulk of the sample. This method was applied using a precision system for the motion for the Mössbauer source. It is shown that the parameters of the hyperfine interactions in the surface layer and in the bulk of the film differ, and that these differences increase towards the surface. This result is explained by the fact that the surface layer is formed as the substrate, together with the synthesized film, is removed from the flux and, consequently, the temperature conditions of synthesis of the bulk and of the surface layer are different. 相似文献
7.
Z. V. Golubenko L. P. Ol’khovik Yu. A. Popkov Z. I. Sizova A. S. Kamzin 《Physics of the Solid State》1998,40(10):1718-1720
The anisotropy of a system of barium ferrite particles with an average diameter of 60 nm has been studied. The effective anisotropy
constant has been determined in the temperature range from 4.2 K to T
c by the law governing approach to saturation magnetization. The observed deviation from the magnetocrystalline anisotropy
constant is explained as due to a negative contribution of the “surface” anisotropy constant. An estimate is made of this
contribution as a function of particle size.
Fiz. Tverd. Tela (St. Petersburg) 40, 1894–1897 (October 1998) 相似文献
8.
L. P. Ol’khovik Z. I. Sizova E. V. Shurinova A. S. Kamzin 《Physics of the Solid State》2010,52(2):311-316
This paper reports on a study of the field and temperature dependences of the parameters of the particle magnetic interaction
in a densely packed system of nanocrystals of the highly anisotropic hexagonal ferrite BaFe12O19 with the particles distributed in diameter within the range 10—100 nm and having volumes satisfying the criterion of “small
Stoner—Wohlfarth particles.” It is shown that the resultant particle interaction in the temperature range 300 K≤T≤640 K has a negative sign, whereas for T>640 K, it is positive. The maximum values of the parameter Δm allow classification of the interaction as moderate in strength. The temperature dependences of the interaction parameters
are found to correlate with manifestation of the size and surface effects in the system, which are characteristic of small
particles (transition to the superparamagnetic state, “surface” anisotropy, and reduced exchange interaction in a structurally
defective near-surface layer of particles). 相似文献
9.
Sunita Keshri Vivekanand Kumar Piotr Wiśniewski Alexander S. Kamzin 《Phase Transitions》2013,86(5):468-476
In this paper we study the structural, morphological and magnetic properties of La0.67Sr0.33MnO3 (LSMO) manganite nanoparticles (NPs) and its biocomposite, obtained by mixing NPs of hydroxyapatite (HA). From the studies of X-ray diffraction and Fourier transmission of infrared spectroscopy it is evident that in the biocomposite sample both the individual phases are distinguishable from each other. The measurements of direct current (DC) magnetization and hysteresis loops reveal that the basic magnetic behaviour of LSMO–HA is similar to that of LSMO; however, the admixture of HA makes the sample magnetically softer. From the investigation of transmission electron microscopy it is observed that such a biocomposite is composed of the NPs of LSMO surrounded by HA particles, which can be found suitable for biomedical applications. 相似文献
10.
Investigation of magneto-anisotropy field for system of particles with near superparamagnetic volume
L.P. Ol’khovik A.S. Kamzin E.L. Karyakina Z.I. Sizova E.V. Shurinova 《Journal of magnetism and magnetic materials》2008
We obtained the temperature dependence for low-field boundary of the anisotropy field distribution in a system of barium hexaferrite nanocrystals in the temperature range from 300 to 700 K. We treated the experimental data taking into account the influence of thermal fluctuations on the anisotropy field and the transition of particles into the paramagnetic state, stimulated by external magnetic field. We showed that the dependence under consideration is formed by particles of different volume, which increased from 3.5×10−18 to 40×10−18 cm3 while the particles lost their magnetic stability with the temperature growth. 相似文献