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1.
S. V. Ovsyannikov Yu. A. Grigor’eva G. V. Vorontsov L. N. Luk’yanova V. A. Kutasov V. V. Shchennikov 《Physics of the Solid State》2012,54(2):261-266
This paper reports on a study of the Seebeck coefficient and power factor κ of p-Bi2 − x Sb x Te3 solid solutions with different contents of antimony atoms in the bismuth sublattice for x = 0, 1.4, 1.5, and 1.6 under variation of pressure of up to 15 GPa. The magnitude of κ has been found to grow nonmonotonically within the pressure region of 2–4 GPa. The effective mass of the density of states m/m 0 and the mobility μ0 have been calculated with due account of degeneracy within the parabolic model of the energy spectrum assuming isotropic charge carrier scattering. It has been shown that application of pressure brings about a decrease of the effective mass m/m 0 and an increase of carrier mobility. The power factor κ of the p-Bi0.6Sb1.4Te3 composition exhibits at the pressure P ≈ 4 GPa the largest increase of the power factor κ as a result of a weak decrease of the effective mass m/m 0 and an increase of carrier mobility as compared to the other solid solution compositions. The specific feature of the variation of the power factor κ with a change of the pressure in bismuth telluride near P ≈ 3 GPa, which is accompanied by formation of a knee in the m/m 0 vs. P dependence, can be assigned to an electronic topological transition. 相似文献
2.
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
3.
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
4.
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
5.
S. F. Dubinin V. I. Sokolov V. I. Maksimov V. D. Parkhomenko N. N. Kolesnikov A. V. Korolev 《Physics of the Solid State》2010,52(5):1107-1110
Neutron diffraction and magnetic measurements have been used to study the effect of doping with Mn3+ ions on the fine crystal structure of the Ga2Se3 monoclinic compound. It has been established that the structural state of the crystals is changed even at a relatively low
doping level (x = 0.04). Arguments in favor of the fact that local Jahn-Teller distortions are responsible for the formation of the fine
structure and magnetism in compounds of this class are presented. 相似文献
6.
I. B. Krynetskii A. Krapf V. P. Martovitskii N. P. Shabanova S. Yu. Gavrilkin V. I. Kovalenko A. P. Rusakov A. I. Golovashkin 《Bulletin of the Lebedev Physics Institute》2011,38(12):349-353
The thermal expansion of single crystals of the Bi2Sr2−x
La
x
CuO6+δ
high-temperature superconducting (HTSC) system in the insulating phase with compositions having no superconducting transition
to a temperature of 1.8 K (x ≥ 0.8) is measured in an arbitrary direction in the (ab) plane in the temperature range of 7–50 K. Temperature regions of material compression upon heating are found. The study
of anomalies in magnetic fields of 3 and 6 T, parallel and perpendicular to the c-axis revealed an anisotropic and nonmonotonic effect of the field on thermal expansion. Such anomalies for the n-type Nd2−x
Ce
x
CuO4−δ
HTSC sample also having no superconducting transition are detected for the first time. The results show that the anomaly
nature is caused by anisotropic electronic ordering, probably, by the charge density wave in the CuO2 plane and superconductivity fluctuations in the insulating phase. 相似文献
7.
8.
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
9.
Kuldeep Chand Verma R. K. Kotnala N. S. Negi 《Applied Physics A: Materials Science & Processing》2009,96(4):1009-1015
The effect of nanosize grains to enhance dielectric tunability in chemically prepared (Pb1−x
Sr
x
)TiO3 (PST) (x=0.1 to 0.5) thin films has been observed. The grain size is evaluated from X-ray diffraction patterns and atomic force microscopy.
The average grain size lies in the range of 80–23 nm with varying Sr content. The nanosize grains in the PST films control
the dielectric behavior up to the higher frequency region and exhibit large tunability with low loss factor at room temperature.
The current–voltage characteristics show a large tunability as electron transport takes place within a highly resistive Fermi
gap. 相似文献
10.
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
11.
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
12.
Kh. Kh. Ismoilov A. M. Abdugafurov Sh. A. Mirsagatov A. Yu. Lederman 《Physics of the Solid State》2008,50(11):2033-2039
The current-voltage and capacitance-voltage characteristics of the n-CdS/p-CdTe heterosystem are investigated. An analysis of the results obtained has demonstrated that a high-resistance i layer (the CdTe1 − x
S
x
solid solution), which is inhomogeneous not only in the electrical conductivity but also in the composition, is formed at
the n-CdS/p-CdTe heterointerface. The thicknesses of the solid-solution layers are estimated from the capacitance-voltage characteristics,
and regions with different types of conduction are found to exist in the intermediate layer. It is shown that the ambipolar
diffusion and drift in the high-resistance CdTe1 − x
S
x
solid-solution layers are directed toward each other, thus resulting in the appearance of a sublinear portion in the current-voltage
characteristics described by the dependence V = exp(Iaw). The observation of a sublinear portion in the current-voltage characteristics measured in both the forward and reverse
electric current directions over a wide temperature range 77–323 K suggests that the diffusion-drift regime can occur in different
parts of the i layer, depending on the electric current density and the ambient temperature. The changes observed in the electric current
and capacitance, as well as in the current-voltage and capacitance-voltage characteristics, after ultrasonic irradiation indicate
that, in the CdTe1 − x
S
x
solid solutions, there exist metastable states, which most probably decay under ultrasonic irradiation and then again form
solid solutions with more stable states.
Original Russian Text ? Kh.Kh. Ismoilov, A.M. Abdugafurov, Sh.A. Mirsagatov, A.Yu. Leĭderman, 2008, published in Fizika Tverdogo
Tela, 2008, Vol. 50, No. 11, pp. 1953–1957. 相似文献
13.
W.-M. Zhu L.-W. Su Z.-G. Ye W. Ren 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,71(3):377-381
The solid solution of (1-x)BiFeO3-xDyFeO3 was prepared by solid
state reactions in the form of ceramics. The effects of chemical
modification by means of aliovalent ionic substitution of Ti4+ for
Fe3+ on the structure and dielectric properties were investigated. A
morphotropic phase boundary bridging the perovskite rhombohedral phase and
the orthoferrite orthorhombic phase was identified at x around 0.1. The
chemical modification was found to stabilize the perovsite phase. The
dielectric performance of the solid solution was improved by the
substitution of Ti4+ for Fe3+, which decreased the electric
conductivity by reducing oxygen vacancies, as evidenced by the decrease in
loss tangent values. Magnetic hysteresis and large saturated magnetization
(0.5 μB/f.u.) were realized in 0.92BiFeO3-0.08DyFeO3
with 2% substitution of Ti4+ for Fe3+, which is believed to
arise from the disruption of the spiral spin modulation after structural
modification, and the interaction between the spins of the Dy3+ and
Fe3+ at low temperatures which decouples the antiferromagnetic order
between the Fe3+ ions. 相似文献
14.
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
15.
First-principles calculations are applied to investigate the effect of biaxial strain on the band gap of wurtzite Al
x
Ga1−x
N. The band gap and band gap bowing parameter increase with compressive strain and decrease with tensile strain. The strain-induced
changes in the band gap of Al
x
Ga1−x
N are linear in the strain range of about −1% to 1% while the linearity is invalid out of the range. The linear coefficient
B(x), characterizing the relationship between the band gap and the biaxial stress, with a quadratic form is obtained. The value
of the band gap bowing parameter decreases from 1.0 eV for −2% strain to 0.91 eV for unstrained and to 0.67 eV for 2% strain. 相似文献
16.
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
17.
M. S. Lebedev 《Optics and Spectroscopy》2009,107(5):776-779
Capabilities of the method of laser null ellipsometry for the study of optical parameters of thin films of multicomponent
alloys are demonstrated. Films of alloys (HfO2)
x
(Al2O3)1 − x
on single-crystal silicon are obtained by the chemical vapor deposition with the use of the following volatile compounds:
hafnium dipivaloylmethanate (IV) and aluminum acetylacetonate (III). The selection of initial sets for their optical parameters
is justified. The selected model is shown to correspond to experimental data. In films deposited from the mixture of precursors,
the refractive index increases from a substrate to a film surface. Due to the separation of sources, films described by a
single-layer model were deposited. This fact is indicative of the homogeneous distribution of components over the film thickness. 相似文献
18.
V. A. Kulbachinski? V. G. Kytin P. M. Tarasov 《Journal of Experimental and Theoretical Physics》2010,110(4):618-621
The effect of gallium on the temperature dependences (5 K ≤ T ≤ 300 K) of Seebeck coefficient α, electrical conductivity σ, thermal conductivity k, and thermoelectric efficiency Z of mixed p-(Bi0.5Sb0.5)2Te3 semiconductor single crystals is studied. The hole concentration decreases upon gallium doping; that is, gallium causes a
donor effect. The Seebeck coefficient increases anomalously, i.e., much higher than it should be at the detected decrease
in the hole concentration. This leads to an enhancement of the thermoelectric power. The observed changes in the Seebeck coefficient
indicate a noticeable gallium-induced change in the density of states in the valence band. 相似文献
19.
N. P. Stepanov A. A. Kalashnikov A. K. Gil’fanov V. M. Grabov Yu. V. Ulashkevich L. D. Ivanova Yu. V. Granatkina 《Optics and Spectroscopy》2011,111(6):912-918
We study IR polarized reflection spectra of solid solutions (Bi2−x Sb x )Te3 (0 < x < 1) in the temperature range 78–293 K and in the excitation range of plasma oscillations of free charge carriers. We reveal that, as the content of Sb2Te3 in the solid solution increases from 0 to 50%, the anisotropy of both plasma frequencies and magnetic susceptibility vary insignificantly. This indicates that, at 293 K, these crystals do not show significant changes in the composition of groups of free carriers near the chemical potential level. We have found that to describe the observed anisotropy of plasma frequencies, it is necessary to take into account the effect of heavy holes of the valence band. This is also confirmed by the results of the study of the temperature behavior of plasma reflection spectra, which exhibit regularities that are similar to anomalous temperature changes of the Hall coefficient. We show that a decrease in plasma frequencies with increasing temperature cannot be described by an increase in the effective mass of charge carriers in accordance with the expression m* ∼ T 0.17, which was obtained upon interpretation of temperature dependences of a number of kinetic coefficients. We use the empirical Moss rule ɛ∞2 E g to estimate the rate of decrease of the thermal band gap dE g /dT = −1.6 × 10−4 eV/deg in a crystal that contains 25% Sb2Te3. 相似文献
20.
Wanwimon Banlue Naratip Vittayakorn 《Applied Physics A: Materials Science & Processing》2008,93(2):565-569
The solid solution between the antiferroelectric PbZrO3 (PZ) and relaxor ferroelectric Pb(Co1/3Nb2/3)O3 (PCoN) was synthesized by the columbite method. The phase structure and thermal properties of (1−x)PZ–xPCoN, where x=0.0–0.3, were investigated. With these data, the ferroelectric phase diagram between PZ and PCoN has been established. The
crystal structure data obtained from XRD indicates that the solid solution PZ–PCoN, where x=0.0–0.3, successively transforms from orthorhombic to rhombohedral symmetry with an increase in PCoN concentration. The AFE→FE
phase transition was found in the compositions of 0.0≤x≤0.10. The AFE→FE phase transition shift to lower temperatures with higher compositions of x. The width of the temperature range of FE phase was increased with increasing amount of PCoN. It is apparent that the replacement
of the Zr4+ ion by (Co1/3Nb2/3)4+ ions would decrease the driving force for antiparallel shift of Pb2+ ions, because they interrupt the translational symmetry. This interruption caused the appearance of a rhombohedral ferroelectric
phase when the amount of PCoN was more than 10 mol%. 相似文献