共查询到20条相似文献,搜索用时 31 毫秒
1.
L. G. Antoshina E. N. Evstaf’eva A. I. Kokorev A. S. Koz’min 《Physics of the Solid State》2005,47(9):1687-1691
The temperature dependence of the susceptibility of the paraprocess χpara (T) is investigated for samples in the CuGaxAlxFe2?2xO4 (x = 0.2, 0.3, 0.4, 0.5, 0.6, 0.7), CuGaxAl2xFe2?3xO4 (x = 0.1, 0.2, 0.3, 0.4, 0.5), and GaxFe1? xNiCrO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8) systems. It is found that long-range magnetic order arises in spinel ferrites at the temperature Ttran of the transition from a cluster spin-glass state to a frustrated magnetic structure with a maximum in the temperature dependence of the susceptibility of the paraprocess. 相似文献
2.
Mössbauer spectra of copper ferrites CuGa x Al2x Fe2 ? 3x O4 (x = 0.3, 0.4, 0.5) have been measured at temperatures in the range from 90 to 295 K. The degree of disturbance of long-range magnetic order has been determined as a function of the temperature. The Curie temperature has been found for the composition with x = 0.5, and the dependence of the Curie temperature on the concentration of the nonmagnetic impurity has been constructed. 相似文献
3.
Mössbauer spectra of the CuGa x Al2x Fe2 ? 3x O4 system (x = 0.1, 0.2, 0.3, 0.4, 0.5) have been studied at a temperature of 295 K. The results obtained are compared with Mössbauer data for the CuGa x Al x Fe2?2x O4 system. It is established that the hyperfine magnetic fields H B (for octahedral sites) and H A (for tetrahedral sites) for ferrites in both systems with ferrimagnetic ordering decrease linearly depending on the total number of nonmagnetic ions in octahedral and tetrahedral sites of the two systems. 相似文献
4.
E. V. Voronina A. G. Ivanova A. K. Arzhnikov A. I. Chumakov N. I. Chistyakova A. V. Pyataev A. V. Korolev 《Physics of the Solid State》2018,60(4):730-737
Results of structural, magnetic, and Mössbauer studies of quasi ordered alloys Fe65Al35 ? xM x (M x = Ga, B; x = 0, 5 at %) are presented. The magnetic state of examined structurally–single-phase alloys at low temperatures is interpreted from the viewpoint of magnetic phase separation. An explanation is proposed for the observed behavior of magnetic characteristics of Fe65Al35 and Fe65Al30Ga5 in the framework of the model of two magnetic phases, a ferromagnetic-type one and a spin density wave. The boron-doped alloy Fe65Al30B5 is shown to demonstrate behavior that is typical of materials with the ferromagnetic type of ordering. 相似文献
5.
K. V. Pokholok D. S. Filimonov M. G. Rozova O. A. Tyablikov 《Bulletin of the Russian Academy of Sciences: Physics》2017,81(7):869-873
New La/Zn substituted strontium ferrites Sr(2 ?x)La x [Fe(2 ? x)Zn x ]O5, (0 ≤ x ≤ 0.3) with brownmillerite- type structure are obtained and studied via X-ray phase analysis and Mössbauer spectroscopy. Depending on the conditions of synthesis, substituting Zn2+ cations can either mainly occupy tetrahedral positions in a brownmillerite structure, or be uniformly distributed between the tetrahedral and octahedral positions. It is shown that they are reversibly oxidized by atmospheric oxygen at elevated temperatures. 相似文献
6.
S. A. Vyzulin D. A. Kalikintseva E. L Miroshnichenko V. Yu. Buz’ko A. I. Goryachko 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(8):943-945
Ferromagnetic resonance (FMR) characteristics are investigated for NixZn1 ? xFe2O4 ferrites (where x = 0.25, 0.5) synthesized using different organic complexation agents. The microstructure of the synthesized ferrites is studied, and the effect complexation agents have on their microstructure and FMR characteristics is determined. 相似文献
7.
E. V. Solodov A. A. Opalenko A. I. Firov A. S. Ilyushin Z. S. Umhaeva 《Moscow University Physics Bulletin》2011,66(3):267-271
The structural transformations and magnetic phase transitions in the quasibinary system Y(Fe1 ? x Al x )2 have been investigated by Mössbauer spectroscopy, X-ray diffractometry, and magnetic measurements of polycrystals. 相似文献
8.
H. S. M. Al’Azzavi A. B. Granovskii Yu. E. Kalinin V. A. Makagonov A. V. Sitnikov O. S. Tarasova 《Physics of the Solid State》2016,58(5):938-945
Films of composites (Co45Fe45Zr10)x(Al2O3)100–x, (Co84Nb14Ta2)x(SiO2)100–x, (Co41Fe39B20)x(SiO2)100–x and multilayer heterogeneous composite–composite structures {[(Co45Fe45Zr10)x(Al2O3)100–x]/[(Co45Fe45Zr10)x(Al2O3)100–x + N2]}n, {[(Co45Fe45Zr10)x(Al2O3)100–x]/[(Co45Fe45Zr10)x(Al2O3)100–x + O2]}n, {[(Co41Fe39B20)x(SiO2)100–x]/[(Co41Fe39B20)x(SiO2)100–x + O2]}n, and {[(Co84Nb14Ta2)x(SiO2)100–x]/[(Co84Nb14Ta2)x(SiO2)100–x + O2]}n have been deposited using the ionbeam sputtering method with a cyclic supply of reaction gases during deposition. The structure and magnetic properties of the films have been studied. It has been shown that the introduction of an oxidized interlayer makes it possible to suppress the perpendicular magnetic anisotropy in the (Co45Fe45Zr10)x(Al2O3)100–x composite with the metallic phase concentration higher than the percolation threshold. 相似文献
9.
The crystal structure and magnetic properties of the Bi1 ? x Ca x Fe1 ? x/2Nb x/2O3 system were studied. It is shown that, at x ≤ 0.15, the unit-cell symmetry of solid solutions is rhombohedral (space group R3c). Solid solutions with x ≥ 0.3 have an orthorhombic unit cell (space group Pbnm). The rhombohedral compositions are antiferromagnetic, while the orthorhombic compositions exhibit a small spontaneous magnetization due to Dzyaloshinski?-Moriya interaction. In CaFe0.5Nb0.5O3, the Fe3+ and Nb5+ ions are partially ordered and the unit cell is monoclinic (space group P21/n). In the concentration range 0.15 < x < 0.30, a two-phase state (R3c + Pbnm) is revealed. 相似文献
10.
A. E. Elsukova N. S. Perov V. N. Prudnikov A. B. Granovskiĭ A. K. Arzhnikov E. P. Elsukov E. V. Voronina E. A. Pechina 《Physics of the Solid State》2008,50(6):1071-1075
The transverse magnetoresistance and the Hall effect of Fe100 ?x Al x ordered alloys with x = 26.5?34.1 at. % are studied at temperatures of 77 and 295 K. No saturation is found in the field dependences up to 17 kOe. The magnetoresistance is negative, depends nonmonotonically on the Al concentration, and reaches a maximum |ΔR/R| = 1.6% in the concentration range from 28 to 30 at. %. The coefficient of the anomalous Hall effect depends nonlinearly on the Al concentration and resistivity: it increases to a lesser extent as compared to the resistivity at x = 26–30 at. % and decreases with increasing resistivity at x > 30 at. %. An explanation is proposed for the observed anomalies in the magnetotransport properties in the framework of the model developed for the inhomogeneous magnetic microstructure of the Fe100 ?x Al x ordered alloys. 相似文献
11.
The 57Fe Mössbauer spectra of the single crystalline and the finely ground Sr1?x La x Fe12?y Co y O19 (x = 0 : y = 0, x = 0.192 : y = 0.152 and x = 0.456 : y = 0.225) samples have been measured to investigate the La-Co substitution effects. All observed spectra at 150 K were well fitted using the five subspectra which correspond to the five crystallographical nonequivalent Fe sites in the M-type hexaferrite, indicating that the valence changes to Fe2+ ions in the Fe3+ ions were not observed in our Sr1?x La x Fe12?y Co y O19 samples. In SrFe12O19, the relative absorption intensities in the five subspectra show the large anisotropies in the recoilless fractions at the five Fe sites whereas these anisotropies were not observed in Sr0.544La0.456Fe11.775Co0.225O19. These results indicate the chemical compositional dependence on the anisotropies of the recoilless fractions at the five Fe sites. The substitution of a Co2+ ion for the Fe3+ ion changes the center shifts of the Fe3+ ions near the Co2+ ion by the perturbation of the Fe-O-Co hybridizations. Therefore, the Co2+ ions occupy the 4f 1 and the 4f 2 sites due to the chemical compositional dependences of the refined magnetic hyperfine field and center shifts of the Fe3+ ions. 相似文献
12.
A. A. Opalenko A. S. Ilyushin A. I. Firov E. V. Solodov Z. S. Umkhaeva 《Physics of the Solid State》2011,53(10):2067-2072
The Pr(Fe1 ? x Al x )2 alloys with concentrations x = 0–1 have been synthesized under a high pressure. The phase composition and lattice parameters (a and c) have been determined as a function of x. The magnetic and Mössbauer measurements have been performed at T = 90–400 K. It has been established that the Curie temperatures of alloys linearly depend on their composition. 相似文献
13.
A. A. Opalenko A. I. Firov A. B. Korshak L. G. Antoshina 《Moscow University Physics Bulletin》2010,65(5):417-420
The Mössbauer spectra of nickel ferrite NiGa x Al x Fe2 ? 2x O4 were measured with significant dilution by nonmagnetic ions (with x = 0.5, 0.7, and 0.8). In the temperature range of 90–295 K, the ratio of the near- and long-range forces was experimentally found and the Curie temperatures were determined. 相似文献
14.
Xing-Feng Zhu Lu Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(4):64
We investigate the electronic and magnetic properties of Fe2MnGa1?x Si x alloy (x = 0, 0.25, 0.5, 0.75, and 1) using first-principles density functional theory within the generalized gradient approximation method. The lattice constant decreases linearly whereas bulk modulus increases with increasing Si content. The total magnetic moment varies linearly with increasing Si content, which follows the Slater-Pauling rule. Electronic band structure calculations indicate that the Fe2MnGa1?x Si x exhibits half-metallic character for all the concentrations studied and the spin polarization and the spin-down band gap both increase with the Si content. Based on the magnetic properties calculations, the Heisenberg exchange coupling parameters give Fe-Mn ferromagnetic coupling and Mn-Mn antiferromagnetic coupling. The T C first decreases and then increases with Si content, which is in well agreement with the experimental results. 相似文献
15.
V. G. Kravets A. N. Pogorelyi A. F. Kravets A. Ya. Vovk Yu. I. Dzhezherya 《Physics of the Solid State》2003,45(8):1530-1536
The reflectivity spectra and the magnetorefractive effect (MRE) of (Co50Fe50)x(Al2O3)1?x metal-dielectric granular films (0.07<x<0.52) are analyzed in the IR spectral range λ=2.5–25 µm. It is revealed that the specific features observed in the spectra at λ≈8.5 and 20 µm are associated with the excitation of phonon modes in the dielectric matrix. The magnetorefractive effect in the films is observed below the percolation thresh-old only in p-polarized light and above the percolation threshold for both the p and s polarizations. It is demonstrated that the optical properties of (Co50Fe50)x(Al2O3)1?x films in the IR spectral range, to a first approximation, can be interpreted in the framework of the effective-medium theory and the magnetorefractive effect can be explained in terms of the modified Hagen-Rubens relation. 相似文献
16.
T. Yu. Kiseleva A. A. Novakova A. N. Falkova T. L. Talako T. F. Grigor’eva 《Moscow University Physics Bulletin》2008,63(4):290-292
Structural studies of nanocomposites produced by the method combining mechanical preactivation of the mixture comprising 8.1% Cr2O3, 65.9% Fe, and 25% Al by mass and self-propagating high-temperature synthesis (SPHTS) have been carried out by Mössbauer spectroscopy methods. It was found that a Fe/Al/Cr2O3 composite with a small Fe2Al5 intermetallic impurity is produced at the mechanical activation stage. At the SPHTS stage, interaction between the activated components of the mixture results in formation of the Fe0.70?x Cr x Al0.3/Al2O3 (x = 0–0.2) composite. 相似文献
17.
Microwave characterization of SrCo x Ti x Fe(12?2x)O19 (x = 0.0, 0.2, 0.3, 0.5, 0.6, 0.7, 1.0) ferrites has been studied as a function of frequency, substitution and thickness, and static electrical current density-electric field characteristics have been investigated as a function of substitution. Microwave characteristics have been measured using power meter in the rectangular slotted waveguide and current density is measured using electrometer. The microwave absorption is evaluated using the standard available model. The results depict ?11.57 dB reflection loss at 10.38 GHz in composition x = 0.6. The electrical current density decreases at lower substitution and increases at higher substitution. The substitution of Co2+ and Ti4+ ions causes enhancement of electromagnetic and static electrical properties. 相似文献
18.
N. I. Medvedeva I. R. Shein O. Yu. Gutina A. L. Ivanovskiĭ 《Physics of the Solid State》2007,49(12):2298-2302
The structural, electronic, and magnetic properties and the enthalpy of formation of iron borocementites Fe3C1?x Bx (x= 0, 0.25, 0.50, 0.75, 1.00) are analyzed using ab initio calculations in the framework of the electron density functional theory. It is found that the unit cell parameter a of the orthorhombic lattice increases linearly and the parameters b and c decrease as the boron concentration increases. The density of states at the Fermi level changes only slightly, and the main variations in the band structure occur in the region of the bottom of the valence bands. The magnetic moment of the iron atoms and the total magnetization and stability of the Fe3C1?x Bx phases increase linearly with an increase in the boron concentration. 相似文献
19.
S. V. Trukhanov M. V. Bushinsky I. O. Troyanchuk H. Szymczak 《Journal of Experimental and Theoretical Physics》2004,99(4):756-765
The structural, magnetic, and electrotransport properties of La1?xSrxMnO3? x/2(0≤x≤0.30) manganites with perovskite structure are investigated experimentally as a function of oxygen deficiency. In the solid solutions La1?xSrxMnO3, a change in the type of symmetry of the unit cell is observed at x=0.125. Samples with x≤0.125 are characterized by an O′-orthorhombic unit cell, whereas samples with x>0.125 are characterized by a rhombohedral unit cell. The structural properties of the anion-deficient solid solutions La1?xSrxMnO3?x/2 are analogous to those of the stoichiometric system. It is assumed that, as the oxygen content decreases, La1? xSrxMnO3?x/2 anion-deficient solid solutions experience a series of successive magnetic phase transformations in the ground state: from an A-type (x=0) antiferromagnet to a cluster spin-glass-type inhomogeneous magnetic state (0.175>x≤0.30) through a two-phase (antiferromagnetic and ferromagnetic) state (0>x≤0.175). The anion-deficient solid solution with x=0.175 has the maximal value of the ferromagnetic component. As the oxygen deficiency increases, the resistivity of La1? xSrxMnO3?x/2 samples first decreases (up to a value of x=0.175), acquiring an activation character, and then increases (up to a value of x=0.30). In this case, none of the anion-deficient solid solutions exhibits a metal-semiconductor transition in the whole range of concentrations considered. A peak of magnetoresistance at a temperature below the point of magnetic ordering is observed only in the sample with x=0.175. The results of experiments carried out with a series of La1?xSrxMnO3?x/2 anion-deficient solid solutions are summarized in the concentration diagrams of the spontaneous magnetic moment and the critical temperature of magnetic phase transitions. Hypothetical magnetic phase states are pointed out. The experimental results obtained can be interpreted in terms of the phase-separation model and the competition between ferromagnetic and antiferromagnetic indirect superex-change interactions. It is assumed that Mn3+-O-Mn3+ indirect superexchange interactions in the orbitally disordered phase are positive in the case of octahedral coordination of manganese ions and are negative when the coordination of at least one Mn3+ ion is pentahedral. 相似文献
20.
L. D. Zaripova N. V. Boltakova A. A. Valiullin Sh. Sh. Bashkirov 《Technical Physics》2005,50(4):473-478
Complex perovskite-like oxides, such as LnFe2/3Mo1/3O3 orthoferrites, Ln8?ySryCu8?xFexO20 (8-8-20), Pr4BaCu4FeO13-δ(4-1-5), YBa2-yLa y Cu3-xFe x O7-δ and Y1-yCa y Ba y La y Cu3-xFe x O7-δ (1-2-3), are studied by means of Mössbauer spectroscopy. At room temperature, the spectra of the orthoferrites contain only magnetic components. The spectra of the 1-2-3 compounds contain only magnetically disordered components: iron atoms substitute for copper at Cu(1) sites, taking various configurations: planar squares, quadratic pyramids, and octahedra. Cuprates 8-8-20 and 4-1-5 have a wide diversity of spectra. In the 8-8-20 oxides, a phase related to the pyramidal environment of the iron cations is present at any iron concentration. In all the perovskites, iron cations become magnetically ordered only at octahedral sites of the structure. 相似文献