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1.
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
2.
M. V. Gorev I. N. Flerov Ph. Sciau S. Guillemet-Fritsch 《Physics of the Solid State》2009,51(4):790-796
Deformation and the thermal expansion coefficient of ceramic samples of (Ba1 − x
La
x
)Ti1 − x/4O3 solid solutions (x = 0, 0.026, 0.036, 0.054) were studied in the temperature range 120–700 K. Based on an analysis of the data obtained, the
temperature-composition phase diagram is refined, and the temperature dependence of the polarization is calculated. The results
are discussed in combination with the dielectric measurement data.
Original Russian Text ? M.V. Gorev, I.N. Flerov, Ph. Sciau, S. Guillemet-Fritsch, 2009, published in Fizika Tverdogo Tela,
2009, Vol. 51, No. 4, pp. 746–752. 相似文献
3.
4.
I. O. Troyanchuk D. V. Karpinsky M. V. Bushinskii O. Prokhnenko M. Kopcevicz R. Szymczak J. Pietosa 《Journal of Experimental and Theoretical Physics》2008,107(1):83-89
Systems of solid solutions Bi1 − x
Ca
x
FeO3 (I) and Bi1 − x
CaxFeO1 − x
Ti
x
O3 (II) have been obtained and their properties have been studied using neutronography and M?ssbauer spectroscopy; magnetization
and permittivity have been measured. It is shown that an increase in the concentration of calcium ions in system I for x > 0.2 changes rhombohedral distortions of a unit cell (space group R3c) to tetragonal distortions (space group I4/mcm), while rhombohedral distortions in system II for x > 0.2 are replaced by orthorhombic distortions (space group Pnma). Analysis of the crystal structure has revealed strong anisotropy in vibrations of Bi and O ions in system I compounds.
Systems I and II are characterized by G-type antiferromagnetic ordering of magnetic moments. In system II, spontaneous magnetization
associated with the Dzyaloshinskii-Moriya interaction has been detected. According to M?ssbauer spectroscopy data, iron ions
in compounds I and II are in the trivalent state and charge compensation occurs due to the formation of oxygen vacancies.
The permittivity increases with the calcium concentration.
Original Russian Text ? I.O. Troyanchuk, D.V. Karpinsky, M.V. Bushinskii, O. Prokhnenko, M. Kopcevicz, R. Szymczak, J. Pietosa,
2008, published in Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2008, Vol. 134, No. 1, pp. 105–112. 相似文献
5.
Yu. N. Zakharov A. G. Lutokhin N. A. Korchagina V. G. Kuznetsov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(4):556-558
The temperature dependences of the pyroelectric and dielectric properties of ferroelectric ceramics of the PbZr1 − x
Ti
x
O3 binary system with x = 0.06, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, and 0.35 have been obtained synchronously for each sample in the range of
the structural phase transition between the states with the symmetry space groups R3c ↔ R3m. It is established that the temperatures of this phase transition for unpolarized and polarized samples coincide in the range
0.06 ≤ x ≤ 0.15. In this case, the x−T phase diagram, constructed on the basis of the pyroelectric and dielectric data, is in excellent agreement with the X-ray
diffraction data on single crystals in this concentration range. The effect of dc electric fields from 5 × 105 V m−1 did not lead to any temperature shifts of the R3c ↔ R3m phase transition for the compositions with 0.06 ≤ x ≤ 0.25.
Original Russian Text ? Yu.N. Zakharov, A.G. Lutokhin, N.A. Korchagina, V.G. Kuznetsov, 2008, published in Izvestiya Rossiiskoi
Akademii Nauk. Seriya Fizicheskaya, 2008, Vol. 72, No. 4, pp. 589–591. 相似文献
6.
7.
8.
Jie Song Bing-Lin Hong Jun Zheng Pei Lin Ming-Sen Zheng Qi-Hui Wu Quan-Feng Dong Shi-Gang Sun 《Applied Physics A: Materials Science & Processing》2010,98(2):455-460
Ti-substituted LiMn2O4 (LiMn2−x
Ti
x
O4, x=0, 0.15, 0.30, 0.45, 0.60, and 0.75) has been synthesized using solid-state reactions. Their crystal and electronic structures
were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy
(UPS). XRD data suggested that the lattice parameters of LiMn2−x
Ti
x
O4 increase due to the replacement of Mn by Ti ions. XPS results indicated that the substituted Ti ions were in +4 oxidation
state; consequently, the normal oxidation state of Mn ions has been detected by measuring the binding energy splitting of
Mn 3s states, which decreases with the content of substituted Ti. The valence band spectra suggested that the intensity of
e
g
level of Mn 3d orbitals increased due to the increase of the Mn3+/Mn4+ ratio. 相似文献
9.
硅锗团簇结构与电子性质的研究对于研发新型微电子材料具有重要意义. 将遗传算法和基于密度泛函理论的紧束缚方法相结合, 研究了SimGen(m+n=9)团簇的原子堆积结构和电子性质. 计算结果发现, SimGen(m+n=9) 团簇存在两种低能原子堆积稳定构型: 带小金字塔的五边形双锥堆积和带桥位Ge原子的四面体紧密堆积. 随着团簇内锗原子数目的逐渐增加, 两种堆积结构均出现明显的转变, 其中最低能量的几何结构由单侧带相邻双金字塔的五边形双锥结构转变为双侧带相邻单金字塔的五边形双锥结构. 随着原子堆积结构的变化, 团簇内原子电荷分布及电子最高占据轨道与电子最低未占据轨道的能隙随团簇内所含硅和锗元素组分的不同呈现出明显的差异. 相似文献
10.
A. V. Savinkov A. V. Dooglav H. Alloul P. Mendels J. Bobroff G. Collin N. Blanchard 《JETP Letters》2010,91(2):83-90
Incidence of doped holes in the CuO2 plane on the AF state was studied by Cu(1) nuclear quadrupole resonance (NQR) in slightly doped YBa2(Cu1 − z
Li
z
)3O6 + x
compounds. Inhomogeneous distribution of doped holes in the plane was detected in the low temperature measurements of transverse
(1/T
2) and longitudinal (1/T
1) relaxation rates. We establish that at lower T the holes motion slows down and we estimate that the holes localize finally in restricted regions (∼3 lattice constants)
in the Coulomb potential of the Li+ ions. Also we compared the hole behavior in slightly doped YBa2(Cu1 − z
Li
z
)3O6 + x
samples with that in slightly doped Y1 − y
Ca
y
Ba2Cu3O6. A stronger trapping potential of the in-plane Li+ impurities was concluded as compared to slightly doped Y1 − y
Ca
y
Ba2Cu3O6 compound with out-of-plane Ca2+ impurities. 相似文献
11.
The equilibrium ordering states of A
1−x
B
1+x
alloys are investigated analytically and by computer simulation with the hard-sphere and pair-binding model. The alloy energies
are calculated for the case where an excess of the B component forms a solid solution or precipitates as pure phase particles.
Criteria for pair-binding energies are obtained that define the type of the resulting alloy. The analytical results are presented
for an alloy of arbitrary dimensionality and for any number of coordination spheres involved in interatomic interactions.
Illustrating examples are given for B2 and L10 superstructures and for a two-dimensional square lattice in view of the atomic interaction in the first two coordination
spheres. 相似文献
12.
13.
P. A. Popov P. P. Fedorov V. M. Reiterov E. A. Garibin A. A. Demidenko I. A. Mironov V. V. Osiko 《Doklady Physics》2012,57(3):97-99
The thermal conductivity of single crystals of Ca1 − x
Er
x
F2 + x
(x = 0.01, 0.05, 0.07, and 0.10) and Ca1 − x
Tm
x
F2 + x
(x = 0.02, 0.04, and 0.06) solid solutions is studied in the temperature ranges 50–300 and 298–673 K. With increasing content
of rare-earth elements, the behavior of thermal conductivity in these solid solutions changes from the characteristic of defect
single crystals to glasslike. The concentration dependences of thermal conductivity for the two systems differ insignificantly. 相似文献
14.
V. S. Zakhvalinski? R. Laiho T. S. Orlova A. V. Khokhulin 《Physics of the Solid State》2008,50(1):63-70
The temperature dependences of the magnetic susceptibility χ(T) and the electrical resistivity ρ(T) of ceramic samples of La1 − x
Ca
x
MnO3 with x = 0.67 (LCMO) and La1 − x
Ca
x
Mn1 − y
Fe
y
O3 with x = 0.67 and y = 0.05 (LCMFO) are investigated in magnetic fields B = 50–105 G and the temperature range T = 4.2–400 K. Both samples undergo a transition from the paramagnetic state to a state with charge (orbital) ordering (CO)
at temperatures T
CO ≈ 272 K for LCMO and T
CO ≈ 222 K for LCMFO. The behavior of the paramagnetic phase in the temperature range 320–400 K for LCMO and 260–400 K for LCMFO
is described by the Curie-Weiss law with effective Bohr magneton numbers p
eff = 4.83 μB (LCMO) and 4.77 μB (LCMFO), respectively. The disagreement between the observed positive Weiss temperatures (θ ≈ 175 K (LCMO) and θ ≈ 134 K
(LCMFO)) and negative Weiss temperatures required for the antiferromagnetic ground state can be explained by the phase separation
and transition to the charge-ordered state. The magnetic irreversibility for T < T
CO is accounted for by the existence of a mixture of the ferromagnetic and antiferromagnetic phases, as well as the cluster
glass phase. At low temperatures, doping with iron enhances the frustration of the system, which manifests itself in a more
regular behavior of the decay rate of the remanent magnetization with time. The temperature dependence of the electrical resistivity
in the range of the charge-ordered phase conforms to the variable-range hopping model. The behavior of the electrical resistivity
is governed by the complex structure of the density of localized states near the Fermi level, which includes a soft Coulomb
gap Δ = 0.464 eV for LCMO and 0.446 eV for LCMFO. It is established that the ratio between the localization radii of charge
carriers a for LCMFO and a
und for LCMO is a/a
und = 0.88.
Original Russian Text ? V.S. Zakhvalinskiĭ, R. Laiho, T.S. Orlova, A.V. Khokhulin, 2008, published in Fizika Tverdogo Tela,
2008, Vol. 50, No. 1, pp. 61–68. 相似文献
15.
I. O. Troyanchuk A. N. Chobot N. V. Tereshko O. S. Mantytskaya E. A. Efimova 《Physics of the Solid State》2011,53(7):1340-1347
The magnetic and magnetotransport properties of Pr0.5Sr0.5Mn1 − x
Co
x
O3 (x ≤ 0.5) solid solutions have been investigated using neutron diffraction methods. The magnetization and electrical conductivity
have been measured in magnetic fields up to 140 kOe. It has been established that, during cooling in the temperature range
from 160 to 110 K, the compounds of compositions with a cobalt content x ≤ 0.07 undergo a structural phase transition from the high-temperature ferromagnetic phase to the antiferromagnetic phase.
A further substitution of cobalt for manganese leads to a stabilization of the inhomogeneous dielectric ferromagnetic state,
whereas a state of the cluster spin-glass type has been revealed in compositions with x = 0.15 and 0.20. At x ≥ 0.25, a new magnetic phase with a Curie temperature up to 210 K is formed as a result of the magnetic interaction between
manganese and cobalt ions. A magnetic phase diagram of the system under investigation has been constructed. 相似文献
16.
O. M. Fedorova A. M. Jankin L. B. Vedmid G. A. Dorogina I. A. Zvereva 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(8):1159-1160
The mechanisms of formation of NdSr2− x
Ca
x
Mn2O7 (0 ≤ x ≤ 2.0) solid solution have been studied. The dependence of its volume magnetic susceptibility on the calcium concentration
is obtained. The stability of this solid solution is compared with that of similar solid solutions in lanthanum-containing
systems. 相似文献
17.
Adolfo Franco Thiago Eduardo Pereira Alves Emília Celma de Oliveira Lima Eloisa da Silva Nunes Vivien Zapf 《Applied Physics A: Materials Science & Processing》2009,94(1):131-137
For the first time nanocrystalline magnetic particles of Mg
x
Fe(3−x)O4 with x ranging from 0.5 to 1.5 have been synthesized by a combustion reaction method using iron nitrate Fe(NO3)3.9H2O, magnesium nitrate Mg(NO3)2.6H2O, and urea CO(NH2)2 as fuel without intermediate decomposition and/or calcining steps. X-ray diffraction patterns of all systems showed broad
peaks consistent with cubic inverse spinel structure of MgFe2O4. The absence of extra reflections in the diffraction patterns of as-prepared materials ensures the phase purity. The mean
crystallite sizes determined from the prominent (311) peak of the diffraction using Scherrer’s equation and transmission electron
microscopy micrographs were c.a. 40 nm with spherical morphology. Fourier transform infrared spectra of the as-prepared material
showed traces of organic and metallic salt by-products; however, these could be removed by washing with deionized water. Typical
hysteresis curves were obtained for all specimens in magnetic field up to 14 T between 4 and 340 K. The saturation magnetization
was 48.3 emu/g and 31.3 emu/g, 44.8 emu/g, and 28.4 emu/g for x=1.0 and 0.8 at 4 K and 340 K, respectively. The saturation magnetization, M
s
, of nanoparticles of the MgFe2O4 specimen is about 50% higher when compared to the bulk. The enhanced magnetization measured in our nanoparticles MgFe2O4 specimens may be attributed to the uncompensated magnetic moment of iron ions between the A- and B-sites, i.e., changes in
the inversion factor. Our magnetization results of MgFe2O4 specimens are comparable to the existing data for the same compound but with different particle size and prepared by different
synthesis methods. 相似文献
18.
N. N. Loshkareva A. V. Korolev N. I. Solin E. V. Mostovshchikova S. V. Naumov N. V. Kostromitina A. M. Balbashov 《Journal of Experimental and Theoretical Physics》2009,108(1):88-97
The magnetic, electrical, and optical properties of Ca1 − x
Ce
x
MnO3 (x≤0.12) manganite single crystals are investigated with the aim of revealing the specific features of the multiphase electronic
and magnetic state as a function of the cerium concentration and the atmosphere used for growing single crystals. It is found
that the concentration dependence of the low-temperature magnetization M(x) of the single crystals is shifted toward the high-concentration range as compared to the corresponding dependence of the
polycrystals, which is explained by the predominant cation deficiency. The electrical resistivity and the reflection spectra
of the single crystals in the infrared spectral range indicate that charge carriers exhibit a band nature at temperatures
close to room temperature. The temperature dependence of the electrical resistivity of the single crystal with x = 0.08, which has the maximum magnetization in the studied series of Ca1 − x
Ce
x
MnO3 compounds, unlike polycrystals, exhibits a metallic behavior over the entire temperature range. The G-type antiferromagnetic phase with the Néel and Curie temperatures T
N(G) = T
C = 100 K is characterized by maxima of the electrical resistivity ρ and the magnetoresistance Δρ/ρ = |(ρ0 − ρ
H
)/ρ0| = 38% in the magnetic field H = 90 kOe. The magnetoresistance Δρ/ρ of the single crystals at cerium concentrations x = 0.10 and 0.12 with variations in temperature exhibit three specific features: near the temperature of charge ordering T
co, near the temperature of the magnetic phase transition to the C-type antiferromagnetic phase T
N(C), and near the temperature of the phase transition to the magnetic charge-ordered phase T
N(MCO). An anomalous temperature dependence of the magnetization is revealed for a single crystal with x = 0.10 grown in oxygen at a pressure of 5 atm, which is explained by the presence of regions with hole conductivity due to
cation deficiency. The inhomogeneous electronic and magnetic state is associated with the interrelation of the charge, orbital,
and spin orderings.
Original Russian Text ? N.N. Loshkareva, A.V. Korolev, N.I. Solin, E.V. Mostovshchikova, S.V. Naumov, N.V. Kostromitina, A.M.
Balbashov, 2009, published in Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2009, Vol. 135, No. 1, pp. 98–107. 相似文献
19.
A. T. Kozakov A. V. Nikol’ski? V. P. Sakhnenko A. N. Pavlov V. G. Smotrakov V. V. Eremkin 《Physics of the Solid State》2009,51(7):1385-1389
Spectra of anomalous electron emission from the surface of solid solutions in the (1 − x)PbMg1/3Nb2/3O3 + xPbTiO3 system with x = 0.06, 0.10, 0.13, 0.20, and 0.25 have been studied. While the energy characteristics of the anomalous electron emission
spectra vary monotonically with x, the behavior of integrated intensity was found to be nonmonotonic with a maximum occurring at x = 0.1. According to the proposed interpretation, the results obtained are explained by the effect of the potential barrier
on the electron emission; the potential barrier depends, in turn, on the permittivity ε of the samples.
Original Russian Text ? A.T. Kozakov, A.V. Nikol’skiĭ, V.P. Sakhnenko, A.N. Pavlov, V.G. Smotrakov, V.V. Eremkin, 2009, published
in Fizika Tverdogo Tela, 2009, Vol. 51, No. 7, pp. 1310–1314. 相似文献
20.
I. A. Boiaryntseva A. V. Gektin G. B. Stryganyuk V. N. Baumer A. N. Belsky 《Journal of Applied Spectroscopy》2012,79(4):589-594
Luminescence spectra of Ca0.65Pr0.35F2.35 solid solutions are studied. It is found that, depending on the excitation energy, different kinds of emission centers appear
in these spectra. An interconfigurational 4f 15d1 →4f2 luminescence is typical for single Pr3+ ions in tetragonal sites. Data on the structure of the solid solutions show that the emission centers involved in 1S0 → 4f2 transitions can be attributed to Pr3+ ions contained in clusters. 相似文献