共查询到20条相似文献,搜索用时 62 毫秒
1.
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
2.
A. N. Georgobiani A. Kh. Matiyev S. V. Bulyarski T. A. Matiyeva 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(10):1445-1447
The refractive index dispersion in β-Tl1 − x
Cu
x
InS2 (0 ≤ x ≤ 0.015) crystals has been studied using intrinsic interference. It is shown that these crystals are characterized by anomalous-dispersion
regions at wavelengths slightly exceeding those corresponding to exciton peaks. It is established that, using intrinsic interference,
one can detect excitons in these crystals at room temperature. Modulation of interference patterns is revealed, and explanation
of this phenomenon is proposed.
Original Russian Text ? A.N. Georgobiani, A.Kh. Matiyev, S.V. Bulyarski, T.A. Matiyeva, 2008, published in Izvestiya Rossiiskoi
Akademii Nauk. Seriya Fizicheskaya, 2008, Vol. 72, No. 10, pp. 1523–1525. 相似文献
3.
4.
A. N. Georgobiani A. Kh. Matiyev C. V. Bulyarski T. A. Matiyeva 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(1):129-131
The IR reflection and Raman spectra of β-Tl1 − x
Cu
x
InS2 (0 ≤ x ≤ 0.015) single crystals have been studied in the temperature range 84–300 K. It is shown that partial replacement of thallium
by copper atoms leads to a decrease in the frequencies of the corresponding oscillations in the frequency range 40–500 cm−1 and does not induce (at given concentrations) local oscillations. Analysis of the transformation of the IR reflection spectra
at T
2 ≈ 185 K revealed a ferroelectric phase transition.
Original Russian Text ? A.N. Georgobiani, A.Kh. Matiyev, C.V. Bulyarski, T.A. Matiyeva, 2009, published in Izvestiya Rossiiskoi
Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 1, pp. 138–140. 相似文献
5.
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
6.
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
7.
O. I. Gyrdasova V. N. Krasil’nikov G. V. Bazuev L. Yu. Buldakova M. Yu. Yanchenko 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(8):1113-1116
A original method of synthesis of quasi-one-dimensional Ti1 − x
V
x
(OCH2CH2O)2 (0 ≤ x ≤ 0.13) and Zn1 − x
Co
x
(HCOO)(HOCH2CH2O) (0 ≤ x ≤ 0.3) has been developed. The synthesis products were used as a basis for nanoscale extended Ti1 − x
V
x
O2 and Zn1 − x
Co
x
O oxides. The compounds obtained and products of their thermolysis were investigated by X-ray diffraction, microscopy, IR
spectroscopy, thermogravimetry, and chemical analysis; the shape and size of particles were determined by scanning electron
microscopy. The good prospects of Ti1 − x
V
x
O2 and Zn1 − x
Co
x
O solid solutions as photocatalysts for hydroquinone oxidation are shown. 相似文献
8.
The dielectric properties of the ceramics of (1 − x)BiFeO3 − x(KBi)1/2TiO3 (0.40 < x < 0.85) solid solutions with an orthorhombic structure have been studied using impedance spectroscopy in the frequency range
25–106 Hz at different temperatures. It has been shown that these solid solutions undergo a diffuse ferroelectric phase transition.
The Curie temperature is found to be in the range 620–640 K. The activation energies of dielectric polarization relaxation
(δE
M
) and dc charge carriers (ΔE
dc) are determined. It has been established that, in the vicinity of 460 K, ΔE
dc increases jumpwise as the temperature increases. 相似文献
9.
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
10.
A. A. Pavelko A. G. Lutokhin S. I. Raevskaya Yu. N. Zakharov M. A. Malitskaya I. P. Raevskii I. N. Zakharchenko E. I. Sitalo N. A. Korchagina V. G. Kuznetsov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(8):1104-1106
(1 − x)PbFe1/2Nb1/2O3−x
PbTiO3 (PFN-xPT) ferroelectric ceramics with low dielectric loss and pronounced anomalies of dielectric and pyroelectric properties near
the ferroelectric-ferroelectric phase transition was obtained by doping with lithium. The temperature dependence of the position
of the morphotropic boundary between the rhombohedral (monoclinic) and tetragonal phases in the x-T phase diagram of the PFN-xPT system was determined for the first time. 相似文献
11.
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
12.
S. F. Dubinin V. I. Sokolov V. D. Parkhomenko S. G. Teploukhov N. B. Gruzdev 《Physics of the Solid State》2008,50(12):2285-2288
The magnetic state and the structure of a Zn1 − x
Ni
x
Se (x = 0.0025) bulk crystal were studied at low temperatures. It is revealed that the magnetic and crystal structures below T ≅ 15 K are dependent on the cooling rate of this dilute semiconductor. For example, on fast cooling to 4.2 K, about 10% hexagonal
ferromagnetic phase is formed in the crystal. During heating, the phase disappears at T ≅ 15 K. The results obtained are discussed with allowance for the specific features of the Jahn-Teller distortions in this
compound.
Original Russian Text ? S.F. Dubinin, V.I. Sokolov, V.D. Parkhomenko, S.G. Teploukhov, N.B. Gruzdev, 2008, published in Fizika
Tverdogo Tela, 2008, Vol. 50, No. 12, pp. 2188–2191. 相似文献
13.
V. V. Atuchin V. N. Kruchinin A. V. Kalinkin V. Sh. Aliev S. V. Rykhlitski? V. A. Shvets E. V. Spesivtsev 《Optics and Spectroscopy》2009,106(1):72-77
Optical characteristics of the HfO2 − x
N
x
and TiO2 − x
N
x
films obtained by reactive ion beam sputtering have been investigated by spectral ellipsometry. The chemical composition
of the films was determined using X-ray photoelectron spectroscopy. The nitrogen content in the oxynitride films (determined
by the N2/O2 ratio in the gas mixture during synthesis) reached ≈9 at % for TiO2 − x
N
x
and ≈ 6 at % for HfO2 − x
N
x
. It is found that the dispersion relations n(λ) and k(λ) for the TiO2 − x
N
x
films change from those characteristic of titanium dioxide to those typical of titanium nitride with an increase in the nitrogen
content from 0 to ≈9 at %. The optical parameters of the HfO2 − x
N
x
films depend weakly on the nitrogen content in the range 0–6 at %.
Original Russian Text ? V.V. Atuchin, V.N. Kruchinin, A.V. Kalinkin, V.Sh. Aliev, S.V. Rykhlitskiĭ, V.A. Shvets, E.V. Spesivtsev,
2009, published in Optika i Spektroskopiya, 2009, Vol. 106, No. 1, pp. 77–82. 相似文献
14.
Yu. N. Zakharov A. A. Pavelko A. G. Lutokhin I. N. Andryushina V. Z. Borodin L. A. Reznichenko 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(8):1125-1127
The influence of thermostating at 450°C on the dielectric and pyroelectric properties of PbZr1 − x
Ti
x
O3 polarized ferroelectric specimens the range 0.02 ≤ x ≤ 0.05 has been investigated. An irreversible increase in the temperature of the ferroelectric-antiferroelectric phase transition
was observed in all specimens upon their cooling after exposure to an elevated temperature for more than 1 h. The original
position of the phase-transition point on the temperature scale was not recovered as a result of afterpoling upon cooling
through the Curie temperature. Heating of the same specimens in the bridged mode up to 650°C with subsequent abrupt immersion
in silicone oil at room temperature (hardening) is accompanied by an additional increase in the range of existence of the
antiferroelectric phase from 3 to 15°C with an increase in the x concentration. 相似文献
15.
Yu. B. Bolkhovityanov A. K. Gutakovskii A. S. Deryabin L. V. Sokolov 《Physics of the Solid State》2008,50(10):1857-1861
The dislocation structure of Ge
x
Si1 − x
films (x ∼ 0.4–0.5) grown by molecular epitaxy on Si(001) substrates tilted by 6° about the 〈011〉 axis was studied. It is shown that,
in the tilt direction, edge misfit dislocations (MDs) arise only in the form of short segments lying on the intersections
of 60° MDs. As a result, the total length of edge MDs along the substrate tilt direction is smaller than that along the tilt
axis. The deviation of the substrate surface from the singular plane made it possible to detect a dislocation configuration
that consists of a short segment of an edge MD and two diverging 60° MDs propagating from it in the tilt direction. The formation
of the segment is assumed to begin with simultaneous nucleation of complementary dislocation half-loops that form a short
edge MD on the interface and then propagate on one side as two diverging 60° MD lines.
Original Russian Text ? Yu.B. Bolkhovityanov, A.K. Gutakovskii, A.S. Deryabin, L.V. Sokolov, 2008, published in Fizika Tverdogo
Tela, 2008, Vol. 50, No. 10, pp. 1783–1787. 相似文献
16.
Photoluminescence properties of Y0.75-xGdxAl0.10BO3:Eu3+0.10, 0.05R3+ (R= Sc, Bi) (0.00≤x≤0.45) 下载免费PDF全文
Y$_{0.75 -
x}$GdxAl0.10BO$3:Eu$^{3+}0.10, 0.05R3+
($R$=Sc, Bi) ($0.00 ≤ x ≤ 0.45$) powder samples are prepared
by solid-state reaction and their luminescence properties are
investigated. With the replacement of Y3+$ ions by Sc3+$
(or Bi3+)$ and Gd3+$ ions in (Y,Al)BO$3:Eu, the
intensities of emission at 254 and 147~nm are remarkably improved,
because Sc3+$ ions can absorb UV light and transfer the energy
to Eu3+$ ions efficiently. Moreover, Gd3+$ and Bi$^{3 +
}$ ions act as an intermediate ``bridge' between the sensitizer and
the activator (Eu3+)$ in energy transfer to produce light in
the (Y, Gd)BO$3:Bi3+$, Eu3+$ system more effectively.
After doping an appropriate concentration of Gd3+$ into
Y$_{0.50}$Gd$_{0.25}$Al0.10BO$3:Eu3+_{0.01}$,
Bi$^{3+}_{0.05}$, the emission intensity reaches its maximum, which
is nearly 110{\%} compared with the red commercial phosphor
(Y,Gd)BO$3:Eu and better chromaticity coordinates (0.650, 0.350)
are obtained. 相似文献
17.
Polycrystalline Pb1−x
Sr
x
(Fe0.012Ti0.988)O3 (0.2≤x≤0.4) (PSFT) thin films have been grown on fused quartz substrates by metallo-organic decomposition technique. The grown films
were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), source meter and UV–Vis–NIR spectrophotometer
to determine the structural, microstructural, dc resistivity and optical properties. The XRD pattern confirmed that the PSFT
films has distorted tetragonal single phase, which close to cubic at higher Sr concentration. AFM analysis revealed that the
grains size reduces with increasing Sr concentration and their average values lies in the range of 26–9 nm. The higher values
of dc resistivity of PSFT nano grains indicate that the transmission of light occurs within these grains up to short wavelength.
The refractive index and the extinction coefficient were determined from the optical transmission spectrum in the wavelength
range of 200–1100 nm and compared with that theoretically calculated, when fitted to a single oscillator model. The values
of optical band gap were determined from Tauc’s extrapolation fitting and suggests that the transformation of electrons during
transmission of light through local states within Fermi gap. 相似文献
18.
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
19.
I. Ruiz de Larramendi R. López-Antón J. I. Ruiz de Larramendi T. Rojo 《Applied Physics A: Materials Science & Processing》2008,93(3):655-661
Polycrystalline samples of Pr1−x
Sr
x
Fe0.8Co0.2 O3−δ
(x=0.1, 0.2, 0.3) (PSFC) were prepared by the combustion synthesis route at 1200°C. The structure of the polycrystalline powders
was analysed with X-ray powder diffraction data. The X-ray diffraction (XRD) patterns were indexed as the orthoferrite similar
to that of PrFeO3 having a single-phase orthorhombic perovskite structure (Pbnm). Pr1−x
Sr
x
Fe0.8Co0.2O3−δ
(x=0.1, 0.2, 0.3) films have been deposited on yttria-stabilized zirconia (YSZ) single-crystal substrates at 700°C by pulsed
laser deposition (PLD) for application to thin film solid oxide fuel cell cathodes. The structure of the films was analysed
by XRD, scanning electron microscopy (SEM) and atomic force microscopy (AFM). All films are polycrystalline with a marked
texture and present pyramidal grains in the surface with different size distributions. Electrochemical impedance spectroscopy
(EIS) measurements of PSFC/YSZ single crystal/PSFC test cells were conducted. The Pr0.7Sr0.3Fe0.8Co0.2O3−δ
film at 850°C presents a lower area specific resistance (ASR) value, 1.65 Ω cm2, followed by the Pr0.8Sr0.2Fe0.8Co0.2O3−δ
(2.29 Ω cm2 at 850°C) and the Pr0.9Sr0.1Fe0.8Co0.2O3−δ
films (5.45 Ω cm2 at 850°C). 相似文献
20.
Deepika K. S. Rathore N. S. Saxena 《Applied Physics A: Materials Science & Processing》2010,98(2):441-448
Se58Ge42−x
Pb
x
(9≤x≤20) glasses have been prepared using conventional melt quenching technique. Differential Scanning Calorimetric (DSC) measurements
show single glass transition and double crystallization, which indicate the occurrence of phase separation in the samples.
The phases present in the samples were identified using XRD. The kinetics of the glass transition has been studied in terms
of the variation of glass transition temperature with composition and heating rate. In addition to this, activation energy
of the glass transition (E
t
) has also been evaluated and its composition dependence is also investigated. The thermal stability of these glasses has
been investigated using various stability criteria: Deiztal first glass criterion, ΔT, Saad and Poulain weighted thermal stability, H′ and the S-parameter. The values of these parameters were obtained using various characteristic temperatures such as the glass transition
temperature, T
g
, the onset temperature of crystallization, T
c
, and the peak crystallization temperature, T
p
. The values of stability parameters show that the phase corresponding to second crystallization is more stable than the phase
corresponding to first one. The stability in terms of the lead (Pb) content has been determined considering the values of
stability parameters of the phase corresponding to second peak. It was found that the stability increases with the lead content. 相似文献