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1.
N. B. Ivanova N. V. Kazak Yu. V. Knyazev D. A. Velikanov L. N. Bezmaternykh S. G. Ovchinnikov A. D. Vasiliev M. S. Platunov J. Bartolomé G. S. Patrin 《Journal of Experimental and Theoretical Physics》2011,113(6):1015-1024
Co3O2BO3 and Co2FeO2BO3 single crystals with a ludwigite structure are fabricated, and their crystal structure and magnetic properties are studied
in detail. Substituted ludwigite Co2FeO2BO3 undergoes two-stage magnetic ordering at the temperatures characteristic of Fe3O2BO3 (T
N1 ≈ 110 K, T
N2 ≈ 70 K) rather than Co3O2BO3 (T
N
= 42 K). This effect is explained in terms of preferred occupation of nonequivalent crystallographic positions by iron, which
was detected by X-ray diffraction. Both materials exhibit a pronounced uniaxial magnetic anisotropy. Crystallographic direction
b is an easy magnetization axis. Upon iron substitution, the cobalt ludwigite acquires a very high magnetic hardness. 相似文献
2.
N. B. Ivanova M. S. Platunov Yu. V. Knyazev N. V. Kazak L. N. Bezmaternykh A. D. Vasiliev S. G. Ovchinnikov V. I. Nizhankovskii 《Physics of the Solid State》2012,54(11):2212-2221
Single crystals of cobalt ludwigite Co3O2BO3 with diamagnetic substitution of Ga3+ ions for a part of the cobalt ions have been grown by the flux method. A detailed investigation of the crystal structure and magnetic properties of the compound has been carried out. A preferred character of the occupation of nonequivalent crystallographic positions by gallium has been revealed. It has been found that the effective magnetic moment and the magnetic ordering temperature are decreased compared to those in the original crystal of the Co3O2BO3 ludwigite. It has been noted that the pronounced magnetic anisotropy observed in the crystallographic ab plane of the original material of the Co3O2BO3 composition disappears in the presence of gallium. 相似文献
3.
J. J. Larrea D. R. Sanchez F. J. Litterst E. M. Baggio-Saitovitch 《Hyperfine Interactions》2005,161(1-4):237-246
57Fe Mössbauer spectroscopic studies of iron ludwigite Fe3O2BO3 performed between 4 and 450 K allow the discussion of magnetic spin arrangements and the dynamics of electronic configurations of iron. The observed magnetic transitions are related to charge ordering. 相似文献
4.
Yu.V. KnyazevN.B. Ivanova N.V. Kazak M.S. PlatunovL.N. Bezmaternykh D.А. Velikanov А.D. Vasiliev S.G. Ovchinnikov G.Yu. Yurkin 《Journal of magnetism and magnetic materials》2012,324(6):923-927
The needle shape single crystals Co3−x MnxO2BO3 with ludwigite structure have been prepared. According to the X-ray diffraction data the preferable character of distinct crystallographic positions occupation by Mn ions is established. Magnetization field and temperature dependencies are measured. Paramagnetic Curie temperature value Θ=−100 K points out the predominance of antiferromagnetic interactions. Spin-glass magnetic ordering takes the onset at TN=41 K. The crystallographic and magnetic properties of Co3O2BO3:Mn are compared with the same for the isostructural analogs Co3O2BO3 and CoO2BO3:Fe. 相似文献
5.
Yu. V. Knyazev N. B. Ivanova O. A. Bayukov N. V. Kazak L. N. Bezmaternykh A. D. Vasiliev 《Physics of the Solid State》2013,55(6):1175-1179
A concentration series of single crystals of iron-cobalt ludwigites Co3 ? x Fe x O2BO3 (x = 0.0125, 0.025, 0.050, 0.10, 1.0) has been synthesized. The structure has been studied using X-ray diffraction and Mössbauer effect. A preferred occupation of nonequivalent crystallographic positions by iron in the ludwigite structure has been revealed. It has been found that the valence of substituting iron ions is three. It has been revealed that the structure of the γ-resonance spectrum of Co2FeO2BO3 is complicated due to a composition disorder in the system. 相似文献
6.
I. I. Nazarenko S. N. Sofronova E. M. Moshkina 《Journal of Experimental and Theoretical Physics》2018,126(5):674-682
A comparative analysis of the copper and iron ions bonds exchange energies was conducted for various variants of orderings and distributions of iron ions among crystallographic positions in ludwigite Cu2FeBO5. Analysis showed that the exchange bonds of iron ions play a key role in the formation of magnetic order. The magnetic ordering strongly depends on the distribution of iron ions among the positions. In the case when the Fe3+ is in the same position as in Fe3BO5, the most favorable magnetic structure is similar to the magnetic structure of ludwigite Fe3BO5. In other cases, the type of magnetic ordering is different. 相似文献
7.
Magnetoelectric (ME) nanocomposites containing Ni0.75Co0.25Fe2O4-BiFeO3 phases were prepared by citrate sol-gel process. X-ray diffraction (XRD) analysis showed phase formation of xNi0.75Co0.25Fe2O4-(1−x)BiFeO3 (x=0.1, 0.2, 0.3 and 0.4) composites on heating at 700 °C. Transmission electron microscopy revealed the formation of powders of nano order size and the crystal size was found to vary from 30 to 85 nm. Dispersion in dielectric constant (ε) and dielectric loss (tan δ) in the low-frequency range have been observed. It is seen that nanocomposites exhibit strong magnetic properties and a large ME effect. On increasing Ni0.75Co0.25Fe2O4 contents in the nanocomposites, the saturation magnetization (MS) and coercivity (HC) increased after annealing at 700 °C. The large ME output in the nanocomposites exhibits strong dependence on magnetic bias and magnetic field frequency. The large value of ME output can be attributed to small grain size of ferrite phase of nanocomposite being prepared by citrate precursor process. 相似文献
8.
The spinel FeCoCrO4 has been studied between 4.2 and 538°K. Characteristic Mossbauer spectra of paramagnetic, magnetic and electronic relaxation types have been observed. The Mossbauer parameters for Fe3+ ions situated at tetrahedral (A) and octahedral (B) sites have been calculated. The cation distribution in magnetic and paramagnetic phases is found to be approximately Fe0.53+Co0.52+[Co0.52+Fe0.53+Cr3+]O4. The Neel temperature been determined by the temperature scanning method to be 310±5°K. 相似文献
9.
I. Kashif S.M. Salem H. Farouk S.A. Salah 《Journal of Physics and Chemistry of Solids》2006,67(11):2370-2375
The affect of sulphur on the structural properties of iron sodium diborate glasses having the composition {(100−x)Na2B4O7+xFe2O3}+yS, where x=0.05, 0.15 and 0.25 mol% and Y=0, 2.5 and 5 wt% was studied by infrared, Mossbauer spectroscopy and magnetic susceptibility measurements. It was found that, for samples having 5 mol% Fe2O3 and free from sulphur, the iron ions are present in both Fe2+ and Fe3+ states and also 92% of the total iron enters the glass network as a glass former. The ratio of Fe3+/Fe2+ increases with increasing the iron content for sulphur-free samples and others containing sulphur. This ratio also decreases with increasing the sulphur content. The magnetic susceptibility was found to decrease with increasing the sulphur content. Also, the increase of Fe2O3 content led to a less symmetrical environment of Fe3+ ions and vice versa for the Fe2+ environment. 相似文献
10.
O. A. Bayukov M. M. Abd-Elmeguid N. B. Ivanova N. V. Kazak S. G. Ovchinnikov V. V. Rudenko 《Physics of the Solid State》2004,46(6):1088-1094
The Mössbauer effect in the Fe1? xVxBO3 solid solutions has been measured at 130 and 300 K. The Fe0.05V0.95BO3 composition was studied in the interval 4.2–300 K. The experimental data obtained are described in terms of the model of a dilute magnetic insulator in which atoms of the first coordination sphere provide a major contribution to the hyperfine field at iron nucleus sites. It was found that, at low temperatures, the field Hhf is generated primarily by the iron ion itself and depends only weakly on substitution. The hyperfine interaction parameters in the discrete configuration series 6Fe, 5Fe1V, 4Fe2V, 3Fe3V, and 2Fe4V were deter-mined. The magnitude of the isomer shift suggests that iron in the crystal resides in the trivalent state. 相似文献
11.
V. S. Pokatilov V. S. Rusakov A. O. Makarova V. V. Pokatilov M. E. Matsnev 《Physics of the Solid State》2016,58(2):315-318
Single-phase polycrystalline La0.75Sr0.25Co0.9857Fe0.02O3 samples have been prepared by solidstate ceramic technology. The samples have the rhombohedral structure (space group \(R\bar 3c\)). The studies of perovskite La0.75Sr0.25Co0.9857Fe0.02O3 by Mössbauer spectroscopy on impurity 57Fe nuclei in the temperature range of 5–293 K have revealed the existence of a superparamagnetic relaxation in the temperature range of 100–210 K. The parameters of hyperfine interactions (hyperfine magnetic fields, line shifts, and quadrupole shifts) and the anisotropy energy have been measured, and the frequencies of magnetic moment relaxation of iron ions have been estimated. 相似文献
12.
N. V. Kazak N. B. Ivanova V. V. Rudenko A. D. Vasil’ev D. A. Velikanov S. G. Ovchinnikov 《Physics of the Solid State》2009,51(5):966-969
Ludwigite single crystals of compositions Co3O2BO3 and Co3 − x
Fe
x
O2BO3 (x ≈ 0.14) have been synthesized. The crystal structure is investigated at room temperature, and the magnetization is studied
in the temperature range T = 4.2–100 K in magnetic fields of up to 600 Oe. The orthorhombic symmetry is revealed, and the unit cell parameters are determined.
A number of features are established for the temperature dependence of the magnetization. In unsubstituted Co3O2BO3, two magnetic transitions are found at T
C1 = 43 K and T
C2 = 15 K. At temperatures below 40 K, spin-glass state is revealed. Substitution of iron ions for cobalt ions leads to a noticeable
shift in the magnetic transitions toward the high-temperature range: T
C1 = 83 K and T
C2 = 74 K. A ferromagnetic ordering of the P type is found in the Co3 − x
Fe
x
O2BO3 (x ≈ 0.14) compound.
Original Russian Text ? N.V. Kazak, N.B. Ivanova, V.V. Rudenko, A.D. Vasil’ev, D.A. Velikanov, S.G. Ovchinnikov, 2009, published
in Fizika Tverdogo Tela, 2009, Vol. 51, No. 5, pp. 916–919. 相似文献
13.
I–V curves showing negative differential resistance (NDR) are reported for single crystals of Co2FeO2BO3 at 315 K and 290 K and for Fe3O2BO3 at 300 K, 260 K and 220 K. Resistivity measurements are presented for both systems, parallel and perpendicular to the c axis, in the range 315–120 K. The high hysteretic behavior of the I–V curves in Co2FeO2BO3 around room temperature is discussed and the heat dissipated is estimated, suggesting an increase in the sample temperature of almost 22 K for the I–V curve at 315 K and a dominant contribution of Joule self-heating for the observed NDR. In contrast, insignificant hysteresis is observed on the I–V curves of Fe3O2BO3 around room temperature. The depinning of charge order domains is suggested as the main contribution to the NDR phenomenon for Fe3O2BO3. The high reproducibility of the NDR in the Fe3O2BO3 single crystal allows its use as a low frequency oscillator, as it is demonstrated. 相似文献
14.
N. Guskos G. ZolnierkiewiczJ. Typek A. Blonska-Tabero 《Physica B: Condensed Matter》2011,406(11):2163-2167
Multicomponent vanadates Co3+xFe4−xV6O24 have been synthesized using the solid state reaction method from Co3V2O8 and FeVO4.oxides. The electron paramagnetic resonance/ferromagnetic resonance (EPR/FMR) spectra of 20 samples containing solid state phases formed in the FeVO4-Co3V2O8 system have been recorded at room temperature. The howardevansite structure (H-type phase) is produced, which corresponds to the Co2.616Fe4.256V6O24 formula while a homogeneity range of lyonsite (L-type phase) type structure could be described by the Co3+1.5xFe4−xV6O24 formula (0.476<x<1.667). Considering the values of g-factor and linewidth of each registered spectrum the existence of three types of magnetic centers was inferred and correlated with phases detected by XRD method. 相似文献
15.
Kwang Joo Kim Hee Kyung Kim Young Ran Park Geun Young Ahn Chul Sung Kim Jae Yun Park 《Hyperfine Interactions》2006,169(1-3):1363-1369
Structural transformation and the related variation in magnetic and optical properties of Co3?x Fe x O4 thin films grown by a sol–gel method have been investigated as the Fe composition varies up to x?=?2. The normal spinel phase is dominant below x?=?0.55 and the inverse spinel phase grows as x increases further. Conversion electron Mössbauer spectroscopy (CEMS) measurements indicate that the normal spinel phase have octahedral Fe3+ ions mostly while the inverse spinel phase contain octahedral Fe2+ and tetrahedral Fe3+ ions. For higher Fe composition (x?>?1.22), Co2+ ions are found to substitute the octahedral Fe2+ sites. The measured optical absorption spectra for the Co3?x Fe x O4 films by spectroscopic ellipsometry support the CEMS interpretation. 相似文献
16.
Xiansong Liu Pablo Hernández-Gómez Kai Huang Shixing Qiu 《Journal of magnetism and magnetic materials》2009,321(16):2421-2424
M-type strontium ferrites substituted by La3+-Co2+(Sr1−xLaxFe12−xCoxO19) were prepared by ceramic process. Effects of the substituted amount of La3+ and Co2+ on structure and magnetic properties of Sr1−xLaxFe12−xCoxO19 compounds have systematically been investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and magnetic disaccommodation. In the measurement range from 80 to 500 K, the magnetic disaccommodation is represented by means of isochronal curves. It is well known that magnetic disaccommodation cannot be obviously found in the M-type of pure strontium ferrites. However, three peaks were observed in Sr1−xLaxFe12−xCoxO19, and this behavior is explained in terms of the presence of Fe2+ cation and to the site occupation by the magnetic Co2+ ionic within the hexagonal structure. 相似文献
17.
K. Takahashi Y. Ujuhira K. Kobayashi T. Iriyama T. Konishi 《Hyperfine Interactions》1992,68(1-4):413-416
Among the ternary rare earth-iron-nitrogen compounds, Sm2Fe17Nx, invented and refined by Asahi Chemical Industry Co., Ltd., shows high magnetic anisotropy, intrinsic coercivity and high
saturation magnetization.
Powders of Sm2Fe17, prepared by are melting method, were nitrided in a mixed gas of hydrogen and ammonia to get x=0≈8 samples /1.2/. These samples
have crystal structure of Th2Zn17 and Fe atoms are estimated to locate in 6c, 9d, 18f, and 18h sites /2.3/.
The Mossbauer spectrum of Sm2Fe17N3. z showed several unique magnetic properties. For example, Q.S. due to Fe occupying 18h site shifted to the direction of minus
velocity.
The result indicates that the nitrogen sites are not only 9e but 3b.
CEM spectra of Sm2Fe17Nx powders showed the doublet due to iron oxide indicating that the surface of Sm2Fe17Nx powders were oxidised /4/. but even if they were exposed to strongly oxidative atmosphere, the thickness of the oxidised
layers increased little, resulting no effect to the magnetic properties and to the Mossbauer magnetic parameters of the bulk. 相似文献
18.
E. P. Chukalina T. N. Stanislavchuk M. N. Popova L. N. Bezmaternykh I. A. Gudim 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(11):1563-1565
The magnetic phase transitions and magnetic structures in RFe3(BO3)4 (R = Y, Gd-Er) iron borates have been investigated by the method of erbium spectroscopic probe. The magnetic ordering temperatures have been determined. On the basis of the comparison of the character of splitting of the spectral lines of the probe Er3+ ion in RFe3(BO3)4(R = Y, Dy-Er) iron borates and in GdFe3(BO3)4, a complicated whose magnetic structure is known, a conclusion is drawn about the orientation of the magnetic moments of iron: in dysprosium and terbium iron borates, an easy-axis magnetic structure is implemented, whereas an easy-plane structure occurs in holmium, erbium, and yttrium iron borates. 相似文献
19.
I. A. Gudim A. A. Demidov E. V. Eremin D. K. Shukla 《Physics of the Solid State》2018,60(10):1989-1998
The magnetic and magnetodielectric properties of Ho0.5Nd0.5Fe3(BO3)4 ferroborate with the competing Ho–Fe and Nd–Fe exchange couplings have been experimentally and theoretically investigated. Step anomalies in the magnetization curves at the spin-reorientation transition induced by the magnetic field B ║ c have been found. The spontaneous spin-reorientation transition temperature TSR ≈ 8 K has been refined. The measured magnetic properties and observed features are interpreted using a single theoretical approach based on the molecular field approximation and calculations within the crystal field model of the rare-earth ion. Interpretation of the experimental data includes determination of the crystal field parameters for Ho3+ and Nd3+ ions in Ho0.5Nd0.5Fe3(BO3)4 and parameters of the Ho–Fe and Nd–Fe exchange couplings. 相似文献
20.
Z. Németh E. Kuzmann A. Vértes Z. Homonnay Z. Klencsár J. M. Grenèche J. Hakl K. Vad S. Mészáros B. Lackner K. Kellner G. Gritzner 《Hyperfine Interactions》2006,169(1-3):1241-1246
Eu0.8Sr0.2Fe x Co1?x O3?z CMR perovskites with different iron concentrations (x?=?0, 0.025, 0.075, 0.15, 0.3) were investigated by X-ray diffraction, AC magnetic susceptibility, magnetotransport, as well as 57Fe and 151Eu Mössbauer spectrometry. The valence state of europium ions was found to be trivalent, independently of the iron concentration. 57Fe Mössbauer spectra and magnetic susceptibility of the investigated perovskites presented complementary results for the magnetic transitions. 相似文献