共查询到20条相似文献,搜索用时 187 毫秒
1.
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
2.
Guo-Yu Lan Yang-Wei Lin Zong-Hong Lin Huan-Tsung Chang 《Journal of nanoparticle research》2010,12(4):1377-1388
This article describes the synthesis of highly water-soluble Zn
x
Hg1−x
Se
y
S1−y
quantum dots (QDs) in aqueous solution through a simple photo-assisted reaction between ZnSe QDs and mercury(I) nitrate dihydrate
[Hg2(NO3)2·2H2O]. In order to deduce the optimal synthesis conditions, we varied several parameters, including the concentrations of mercaptosuccinic
acid (MSA) and Hg2(NO3)2·2H2O, the illumination time, and the reaction temperature. When irradiated at temperatures below 80 °C, the ZnSe QDs reacted
with the S2− ions formed rapidly from MSA and the Hg2+ ions formed from Hg2
2+ ions to form Zn
x
Hg1−x
Se
y
S1−y
QDs through a process of photo-etching and surface combination. Under different conditions, we prepared a series of Zn
x
Hg1−x
Se
y
S1−y
QDs that emit fluorescence at the maximum wavelengths ranging from 405 to 760 nm. Inductively coupled plasma-mass spectrometry
and transmission electron microscopy/energy dispersive spectrometry revealed that the content of Hg in the Zn
x
Hg1−x
Se
y
S1−y
QDs was greater when the synthesis was conducted at higher temperature. The Zn0.88Hg0.12Se0.44S0.56 QDs exhibit improved photostability than crude ZnSe QDs and possess long lifetimes (τ1 ~ 38 ns and τ2 ~ 158 ns). 相似文献
3.
S. V. Grigoriev V. A. Dyadkin S. V. Maleyev D. Menzel J. Schoenes D. Lamago E. V. Moskvin H. Eckerlebe 《Physics of the Solid State》2010,52(5):907-913
Two systems of noncentrosymmetric cubic helical magnets Mn1 − y
Fe
y
Si (y = 0.06, 0.08, 0.10) and Fe1 − x
Co
x
Si (x = 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.50) have been compared. The concentration dependences of the critical temperature
and magnetic field have been obtained using small-angle polarized-neutron scattering and analyzed in the framework of the
Bak-Jensen model. It has been established that, among the two interactions that play the main role in these systems, i.e.,
the isotropic symmetric ferromagnetic exchange and the Dzyaloshinskii-Moriya isotropic antisymmetric interaction, the former
interaction determines the critical temperature in the Mn1 − y
Fe
y
Si system and the latter interaction determines this temperature in the Fe1 − x
Co
x
Si system. 相似文献
4.
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
5.
A. A. Lotin O. A. Novodvorsky V. Ya. Panchenko L. S. Parshina E. V. Khaydukov D. A. Zuev V. V. Rocheva O. D. Khramova K. D. Chtcherbachev 《Physics of the Solid State》2011,53(3):467-471
Thin films of Cd
y
Zn1 − y
O and Mg
x
Zn1 − x
O (y = 0−0.35, x = 0−0.45) ternary alloys have been grown by pulsed laser deposition onto sapphire substrates. The record solubility limits
of Cd (y = 0.3) and Mg (x = 0.35) have been achieved in hexagonal zinc oxide. The mismatch of the lattice parameters a of Cd0.2Zn0.8O and Mg0.35Zn0.65O does not exceed 1%; in this case, the band gap discontinuity is 1.3 eV. The surface roughness of the films does not exceed
2.5 nm at x = 0−0.27 and y = 0−0.20. 相似文献
6.
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
7.
G. M. Abramova G. A. Petrakovski? O. A. Bayukov A. F. Bovina V. V. Sokolov 《Physics of the Solid State》2010,52(1):91-95
This paper reports on the results of the synthesis and study of the diffraction patterns and M?ssbauer spectra of single crystals
of homogeneous M
xMn1 − x
S solid solutions with a cubic NaCl structure prepared by the cation substitution of 3d elements for divalent manganese ions in manganese monosulfide. It has been shown that, similarly to the hydrostatic pressure,
the substitution of 3d ions with a smaller ionic radius is accompanied by the contraction of the MnS cubic cell. The calculated lattice parameters
agree with the experimental data. The homogeneous region of the formation of homogeneous solid solutions is limited in composition
x, which depends on the choice of a substitutional cation. 相似文献
8.
A. A. Kozlovskii V. F. Khirnyi A. V. Semenov V. M. Puzikov 《Physics of the Solid State》2011,53(4):707-716
The electrical conductivity and Seebeck effect in ceramics based on cobaltites Ho1 − x
Sr
x
CoO3 − δ (x = 0.65, 0.75, 0.85, 0.95) and Er1 − x
Sr
x
CoO3 − δ (x = 0.75, 0.85, 0.95) with a perovskite-like structure have been investigated in the temperature range T > 77 K. All the compounds under study are characterized by the variable-range-hopping conductivity with the temperature dependence
of the electrical resistivity corresponding to the Mott law. It has been found that, in the Ho0.35Sr0.65CoO3 − δ compound, thermally excited Co3+ ions contribute to the electrical conductivity with an increase in temperature to 250 K. The Seebeck coefficient of the systems
studied decreases as the strontium concentration and temperature increase. It has been shown that, for an adequate explanation
of this behavior, proper allowance must be made for the splitting of the 3d levels, as well as for the charge disproportionation of the cobalt ions. 相似文献
9.
V. S. Rusakov N. I. Chistyakova I. A. Burkovsky A. M. Gapochka T. L. Evstigneeva 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(3):389-393
A M?ssbauer study of the structural and charge states of 57Fe and 119Sn atoms in the compounds of Cu3 −x
Fe
x
SnS4 and Cu2Fe1 − x
Zn
x
SnS4 systems was performed. It was shown that the iron atoms in the compounds of both systems were in the divalent and trivalent
states occupying the tetrahedral positions of the structure. The character of the changes of the degree of covalency of the
Fe2+-S, Fe3+-S and Sn4+-S bonds during the isomorphic substitution in the systems was established. 相似文献
10.
B. Gao J. Shen F. X. Hu J. Wang J. R. Sun B. G. Shen 《Applied Physics A: Materials Science & Processing》2009,97(2):443-447
The influence of Cu substitution for Mn on magnetic properties and magnetic entropy change has been investigated in Heusler
alloys, Ni50Mn35−x
Cu
x
Sn15 (x=2,5 and 10). With increasing Cu content from x=2 to x=5, the martensitic transition temperature, T
M
, decreases from 220 K to 120 K. Further increasing Cu up to x=10 results in the disappearance of T
M
. For samples Ni50Mn33Cu2Sn15 and Ni50Mn30Cu5Sn15, both martensitic and austenitic states exhibit ferromagnetic characteristics, but the magnetization of martensitic phase
is notably lower than that of austenitic phase. The magnetization difference, ΔM, across the martensitic transition leads to a considerably large Zeeman energy, μ
0ΔM⋅H, which drives a field-induced metamagnetic transition. Associated with the metamagnetic behavior, a large positive magnetic
entropy change ΔS takes place around T
M
. For the sample Ni50Mn33Cu2Sn15,ΔS reaches 13.5 J/kg⋅K under a magnetic field change from 0 to 5 T. 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.
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
13.
E. I. Lakhno E. I. Burmakin I. V. Korzun G. Sh. Shekhtman 《Physics of the Solid State》2012,54(3):504-507
The rubidium monoferrite RbFeO2-based solid solutions with the composition Rb2 − 2x
Fe2 − x
P
x
O4 have been synthesized, and their crystal structure and the temperature and concentration dependences of the total and electron
conductivities have been studied. The introduction of P5+ ions has been found to sharply decrease the electron conductivity that prevails in pure rubidium monoferrite and, at the
same time, to increase the ionic conductivity. The latter becomes dominant as the phosphorus concentration increases. The
maximum rubidium-cation conductivity of the materials under study is ∼3 × 10−2 S/cm at 300°C and ∼3 × 10−1 S/cm at 700°C. The results have been compared with the previously obtained data for similar solid solutions based on rubidium
monogallate and monoaluminate. 相似文献
14.
V. D. Sedykh I. I. Zver’kova V. Sh. Shekhtman A. V. Dubovitski? V. I. Kulakov 《Physics of the Solid State》2010,52(3):591-598
The specific features of the structural transformations in La1 − x
Sr
x
Mn0.98Fe0.02O3 + δ (x = 0.05−0.30) as functions of the Sr content have been investigated using M?ssbauer spectroscopy and X-ray diffraction. It
has been shown that, when the Sr content is lower than 10%, three phases are formed: PnmaII, PnmaI, and R-3c. In the Sr concentration range from 10 to 20%, the PnmaI and R-3c phases are formed. At a strontium content of 20%, the rhombohedral phase is formed. When the strontium content increases
to 30%, the presumably monoclinic (distorted cubic) phase is formed in addition to the rhombohedral phase. The specific features
of the formation and suppression of the phases in the LaMn0.98Fe0.02O3 + δ compound are compared with those observed in the strontium-doped La1 − x
Sr
x
Mn0.98Fe0.02O3 + δ compound. The general regularities of the structural transformations and substantial differences between them have been revealed. 相似文献
15.
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
16.
R. S. Iskhakov E. A. Denisova S. V. Komogortsev L. A. Chekanova Yu. E. Kalinin A. V. Sitnikov 《Physics of the Solid State》2010,52(11):2263-2266
This paper reports on the results of the investigation of the relation between the magnetic microstructure and ferromagnetic
resonance (FMR) in ferromagnetic metal-insulator composites by using granular alloys (Co41Fe39B20)
x
(SiO2)1 − x
and Co
x
(SiO2)1 − x
as an example. A comparative analysis of the properties of FMR spectra and parameters of random magnetic anisotropy leads
to correlations between these quantities. It has been found that the main mechanism that determines the FMR line width in
the films under investigation is the exchange narrowing mechanism. 相似文献
17.
I. O. Troyanchuk D. V. Karpinsky M. V. Bushinsky M. I. Kovetskaya E. A. Efimova V. V. Eremenko 《Journal of Experimental and Theoretical Physics》2011,113(6):1025-1031
The crystal structure and magnetic and piezoelectric properties of the Bi1 − x
Ca
x
FeO3 − x/2 system (x ≤ 0.2) are studied. The crystal-structure transformations occur in the following sequence: rhombohedral (R3c) polar phase (x ≤ 0.06) → modulated polar phase (0.07 ≤ x ≤ 0.1) → modulated antipolar phase (0.11 ≤ x ≤ 0.14). The modulated polar and antipolar phases are weakly ferromagnetic with a spontaneous magnetization of 0.25 G cm3/g (x = 0.09). In the polar weak ferromagnet with x = 0.09, a uniform piezoelec- tric response 2.5 times stronger than in the initial BiFeO3 compound is detected by the piezoelectric force microscopy. 相似文献
18.
Ning Tang Bo Shen Kui Han Xiao-Wei He Chun-Ming Yin Zhi-Jian Yang Zhi-Xin Qin Guo-Yi Zhang Tie Lin Wen-Zheng Zhou Li-Yan Shang Jun-Hao Chu 《Applied Physics A: Materials Science & Processing》2009,96(4):953-957
The subband structure and occupation in the triangular quantum well at Al
x
Ga1−x
N/GaN heterointerfaces have been investigated by means of temperature dependent Shubnikov–de Haas (SdH) measurements at low
temperatures and high magnetic fields under illumination. After the illumination of the heterostructures, the total two-dimensional
electron gas concentration increases, and the SdH oscillation amplitudes are enhanced when there is no additional subband
occupation. It is also found that the energy separation between the subbands decreases after the illumination. We suggest
that the illumination decreases the electric field and thus weakens the quantum confinement of the triangular quantum well
at Al
x
Ga1−x
N/GaN heterointerfaces. The GaN layer is thought to be the primary contributor of the excited electrons by the illumination. 相似文献
19.
V. R. Galakhov B. A. Gizhevskii L. V. Elokhina N. N. Loshkareva S. V. Naumov M. Raekers M. Neumann A. M. Balbashov 《JETP Letters》2010,91(3):129-133
The charge states and effective spins of manganese ions in nonstoichiometric single crystals of Ca1 − x
La
y
MnO3 − δ
(x = 0, 0.05, 1) manganites have been determined from the exchange splitting of Mn 3s X-ray photoelectron spectra. The chemical composition of the manganite samples under investigation, including the concentration
of oxygen, has been determined using the data of the X-ray microanalysis of cations. It has been found that the manganite
single crystals under investigation have large defectiveness in both the cation and oxygen sublattices. The efficiency of
the complex use of 3s photoelectron spectroscopy and X-ray microanalysis in the determination of the charge state of manganese ions and violations
of stoichiometry in doped and defected manganites has been demonstrated. 相似文献
20.
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