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1.
The preparation of (La9.33−2x/3Sr
x
□0.67−x/3)Si6O24O2 (0 ≤ x ≤ 2) samples with different amounts of cation vacancies is reported. Structure and unit-cell parameters were deduced by Rietveld
analysis of XRD patterns. Structural features that enhance oxygen conductivity in Sr-doped apatites are discussed. Up to three
components were detected in 29Si MAS-NMR spectra which change with the amount and distribution of cation vacancies. In general, oxygen conductivity increases
with the amount of vacancies at La1 (6h) sites, passing through a maximum for x = 0.4. In the case of activation energy, a minimum is detected near x = 1.2, indicating that entropic and enthalpic change in different ways. The presence of cation vacancies should enhance oxygen
hopping along c-axis; however, the analysis of the frequency dependence of conductivity suggests that oxygen motions are produced along three
axes. 相似文献
2.
The Tl2S compound was prepared in a single crystal form using a special local technique, and the obtained crystals were analysed
by X-ray diffraction. For the resultant crystals, the electrical properties (electrical conductivity and Hall effect) and
steady-state photoconductivity were elucidated in this work. The electrical measurements extend from 170 to 430 K, where it
was found that σ
⊥ = 8.82 × 10−5 Sm−1 when current flow direction makes right angle to the cleavage plane of the crystals. In the same range of temperatures, it
was found that σ
‖ = 4.73 × 10−5 Sm−1 when the current flow is parallel to the cleavage plane. In line with the investigated range of temperatures, the widths
of the band gaps were calculated and discussed as also the results of the electrical conductivity and Hall effect measurements.
In addition, the anisotropy of the electrical conductivity (σ
⊥/σ
‖) for the obtained crystals was also studied in this work. Finally the photosensitivity was calculated for different levels
of illumination as a result of the photoconductivity measurements, which showed that the recombination process in Tl2S single crystals is a monomolecular process.
相似文献
3.
A. U. Sheleg V. G. Hurtavy S. N. Mustafaeva E. M. Kerimova 《Physics of the Solid State》2011,53(3):472-475
The temperature dependences of the electrical conductivity and the permittivity of TlInSe2 and TlGaTe2 crystals unirradiated and irradiated with 4-MeV electrons at a doze of 1016 cm−2 have been investigated. It has been established that electron irradiation leads to a decrease in the electrical conductivity
σ and the permittivity ɛ over the entire temperature range under study (90–320 K). It has been revealed that the TlInSe2 and TlGaTe2 single crystals undergo a sequence of phase transitions characteristic of crystals of this type, which manifest themselves
as anomalies in the temperature dependences σ = f(T) and ɛ = f(T). Electron irradiation at a doze of 1016 cm−2 does not affect the phase transition temperatures of the crystals under investigation. 相似文献
4.
Magnetic and kinetic properties as well as transmission and absorption spectra of Hg
1−x−y
Mn
x
Fe
ySe (0.09 ≤ x ≤ 0.099 and 0.001 ≤ y ≤ 0.01) crystals are investigated at H ≈ 0.5–6 kOe in the temperature range T = 77–300
K. The band parameters are determined on the basis of experimental data. It is found that in the crystals under study at T
≈ 300 K, electron scattering by polar optical phonons dominates, direct optical band-to-band transitions occur, and replacement
of a part of Mn atoms by Fe for x + y = 0.1 results in an increase in Eg
op with Fe content.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 35–39, March, 2007. 相似文献
5.
The crystal structure and magnetic properties of Bi1 − x
A
x
FeO3 − x/2 (A = Ca, Sr, Pb, Ba), Bi1 − x
A
x
(Fe1 − x
Ti
x
)O3, and Bi1 − x
A
x
(Fe1 − x/2Nb
x/2)O3 solid solutions have been studied. It is shown that the homogeneous polar weak ferromagnetic state occurs in the vicinity
of a morphotropic phase boundary in the systems where dopant ions lead to the reduction of the unit cell volume in the polar
phase. In the case of A = Ca, the non-polar phase also exhibits weak ferromagnetism and the spontaneous magnetizations in
the polar and nonpolar phases differ only slightly. 相似文献
6.
Duan’s simple model is extended to analyze the mixing of the 4f
N − 15d configuration with the 4f
N
states. The explicit static coupling and traditional dynamic coupling are considered, and the parameters are fitted according
to the absorption spectrum in LiYF4: Nd3+. The parameter values obtained are as follows: T
32 = −28i × 10−7, T
52 = −1151i × 10−7, A
322 = 192i × 10−12 cm, A
524 = i × 10−12 cm, A
726 = 54i × 10−12 cm, and A
766 = −680i × 10−12 cm. Compared to the experimental measurements, the present model yields better results than those obtained from the Judd-Ofelt
theory.
The text was submitted by the authors in English. 相似文献
7.
Solid polymer electrolytes (SPE) based on poly-(vinyl alcohol) (PVA)0.7 and sodium iodide (NaI)0.3 complexed with sulfuric acid (SA) at different concentrations were prepared using solution casting technique. The structural
properties of these electrolyte films were examined by X-ray diffraction (XRD) studies. The XRD data revealed that sulfuric
acid disrupt the semi-crystalline nature of (PVA)0.7(NaI)0.3 and convert it into an amorphous phase. The proton conductivity and impedance of the electrolyte were studied with changing
sulfuric acid concentration from 0 to 5.1 mol/liter (M). The highest conductivity of (PVA)0.7(NaI)0.3 matrix at room temperature was 10−5 S cm−1 and this increased to 10−3 S cm−1 with doping by 5.1 M sulfuric acid. The electrical conductivity (σ) and dielectric permittivity (ε′) of the solid polymer electrolyte in frequency range (500 Hz–1 MHz) and temperature range (300–400) K were carried out.
The electrolyte with the highest electrical conductivity was used in the fabrication of a sodium battery with the configuration
Na/SPE/MnO2. The fabricated cells give open circuit voltage of 3.34 V and have an internal resistance of 4.5 kΩ. 相似文献
8.
The dependences of the electrical resistivity ρ and the Hall coefficient R on the magnetic field have been measured for single-crystal samples of the n-Bi0.93Sb0.07 semiconductor alloys with electron concentrations in the range 1 × 1016 cm−3 < n < 2 × 1018 cm−3. It has been found that the measured dependences exhibit Shubnikov-de Haas quantum oscillations. The magnetic fields corresponding
to the maxima of the quantum oscillations of the electrical resistivity are in good agreement with the calculated values of
the magnetic fields in which the Landau quantum level with the number N intersects the Fermi level. The quantum oscillations of the Hall coefficient with small numbers are characterized by a significant
spin splitting. In a magnetic field directed along the trigonal axis, the quantum oscillations of the resistivity ρ and the
Hall coefficient R are associated with electrons of the three-valley semiconductor and are in phase with the magnetic field. In the case of
a magnetic field directed parallel to the binary axis, the quantum oscillations associated both with electrons of the secondary
ellipsoids in weaker magnetic fields and with electrons of the main ellipsoid in strong magnetic fields (after the overflow
of electrons from the secondary ellipsoids to the main ellipsoid) are also in phase. In magnetic fields of the quantum limit
ħω
c
/2 ≥ E
F, the electrical conductivity increases with an increase in the magnetic field: σ22(H) ∼ H
k
. A theoretical evaluation of the exponent in this expression for a nonparabolic semiconductor leads to values of k close to the experimental values in the range 4 ≤ k ≤ 4.6, which were obtained for samples of the semiconductor alloys with different electron concentrations. A further increase
in the magnetic field results in a decrease of the exponent k and in the transition to the inequality σ22(H) ≤ σ21(H). 相似文献
9.
S. Yu. Paranchich L. D. Paranchich M. D. Andriichuk V. R. Romanyuk V. N. Makogonenko Yu. V. Tanasyuk T. A. Mel’nichuk 《Journal of Applied Spectroscopy》2007,74(1):81-85
We present the results of experimental studies of the optical properties of cobalt-doped Cd
x
H1−x
Se (x = 0.18) single crystals with cobalt ion concentrations of NCo = 5·1018, 5·1019, and 1·1020 cm−3 at T = 90 K and 300 K. The composition (x = 0.18) of the Cd
x
Hg1−x
Se solid solution was selected so that the hypothetical resonance level is found on the bottom of the conduction band. We
show that the cobalt ions in the mercury selenide can form a resonance donor level only for cobalt concentrations NCo < 5·1018 cm−3. For NCo ∼ 5·1018 cm−3, the cobalt ions substitute for mercury atoms, forming a solid solution and leading to an increase in the bandgap width and
a change in the physical properties. The solubility of cobalt in the HgSe lattice can be greater than 5%–10%.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 73–77, January–February, 2007. 相似文献
10.
O. Cozar I. Ardelean V. Simon L. David N. Vedean V. Mih 《Applied magnetic resonance》1999,16(4):473-480
Two lead-phosphate glass systems doped with both copper and vanadium ions in different ratios were studied by EPR (electron paramagnetic resonance) method. EPR spectra and parameters (g‖ = 2.44, g⊥ = 2.08 andA ‖ = 117.6 · 10−4 cm−1) obtained for x(CuO · V2O5)(l−x)[2P2O5 · PbO] glasses withx ≤ 10 mol% suggest a tetrahedral (Td) coordination of Cu2+ ions and not a tetragonally elongated octahedron as has been assumed in previous works. The ground state of the paramagnetic electron is thed xy copper orbital with a 4pz contribution of 6%. For 20 ≤x ≤ 40 mol% a broad line (ΔB = 307 G) characteristic for clustered ions appears atg = 2.18. The V4+ ions are evidenced only in the spectra of x(CuO · 2V2O5)(1 −x)[2P2O5 · PbO] glasses and the resonance parameters suggest a pentacoordinated C4v local symmetry for these ions. The hyperfine structures characteristic for Cu2+ and V4+ ions disappear for 10 ≤x ≤ 40 mol% due to the mixed exchange Cu2+−V4+ pair formation in these glasses. 相似文献
11.
Ruiting Sun Xiaoli Wang Jing Shi Le Wang 《Applied Physics A: Materials Science & Processing》2011,104(1):129-133
New perovskite solid solution ceramics of (1−x)BaTiO3-xBi(Mg1/2Ti1/2)O3 ((1−x)BT-xBMT, x≤0.09) were synthesized by the solid-state reaction technique. X-ray diffraction studies have revealed a stable single perovskite
structure for all samples. Dielectric measurements were carried out at different frequencies and temperatures. The polarization
evolutions with temperatures were measured to investigate the ferroelectric properties. All the compositions show features
of ferroelectrics with diffuse phase transition, though the temperature T
m
of their dielectric constant maximum ε
m
is frequency dependent. The dielectric constant peak ε(T) of (1−x)BT-xBMT ceramics become broad with increasing BMT content. During the temperature range of ε(T) peak summit, (1−x)BT-xBMT ceramics present quasi-linear dielectric phenomenon under high electric field with very high dielectric constant. 相似文献
12.
The synthesis and electrical characterisation over a range of oxygen partial pressures (10−20 to 1 atm) are reported for the cubic perovskite niobate-titanates Sr1−x/2Ti1−xNbxO3−δ, which are proposed as potential anode materials for solid oxide fuel cells. Single phase samples were observed for 0≤x≤0.4,
and phase purity was retained on annealing at both high and low oxygen partial pressures. Good electrical conductivity was
observed on reduction in low oxygen partial pressures, with a maximum for the sample with 25% Nb (x=0.25), σ=5.6 Scm−1 at 930°C (P (O2)=10−18 atm). For dense samples the higher the Nb content the more resistant the reduced sample was to reoxidation as the oxygen
partial pressure was increased.
Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996 相似文献
13.
I. N. Andryushina K. P. Andryushin O. N. Razumovskaya L. A. Shilkina L. A. Reznichenko Yu. I. Yurasov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(8):1127-1129
The behavior of the relative permittivity ɛ/ɛ0 of PbZr1 − x
Ti
x
O3 (PZT) solid solutions (0.495 ≤ x ≤ 0.51) in the temperature range of 100–300 K at frequencies from 1 × 10−2 to 2 × 107 Hz was investigated. Diffuse, strongly relaxing maxima at T = 230−260 K (x = 0.495−0.505) and 150–160 K (x = 0.510) were observed in the PZT studied. The relaxation processes are well described by the Vogel-Fulcher law, and the
dielectric spectra are approximated by the Cole-Cole formula. 相似文献
14.
R. S. Madatov A. I. Nadzhafov T. B. Tagiev M. R. Gazanfarov M. A. Mekhrabova 《Physics of the Solid State》2011,53(11):2205-2209
The temperature dependence of the electrical conductivity and current-voltage characteristics of γ-irradiated TlInSe2 single crystals with an electrical resistivity of ∼108 Ω cm have been investigated. It has been established that the anomalies of the conductivity observed in weak electric fields
and at low dozes of irradiation are related to the decomposition of neutral complexes containing an interstitial cation atom.
In strong electric fields, a thermal-field ionization of traps occurs. The main mechanism of radiation defect formation is
the formation of complexes [V
In−In
i
+], [V
Se−Se
i
−], and others with the structural defects characteristic of unirradiated crystals. The activation energy, trap concentrations,
and the potential well shape near the traps have been determined. 相似文献
15.
The exciton absorption spectra of thin films of (Cs1 − x
Rb
x
)2CdI4 solid solutions have been investigated and the refractive index n(λ) in their transparency window in the concentration range of 0 ≤ x ≤ 1 has been measured. The exciton-band parameters and optical permittivity ɛ∞(x) have been found to linearly depend on the concentration. It is established that excitons are incorporated into the CdI2 sublattice of the solid solutions and belong to intermediate-coupling ones. The characteristics of excitons in ferroelastics
are compared with the corresponding parameters for CdI2, RbI, and CsI, which are used as components to synthesize ternary compounds. 相似文献
16.
J. R. Suárez F. Estrada O. Navarro M. Avignon 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(1):53-58
We have studied the effect of cationic disorder on the spin polarization of the double
perovskite system
Sr2Fe1+x
Mo1−x
O6
with −1 ≤ x ≤ 1/3. The composition x = 0 corresponds
to the well-known double-perovskite Sr2FeMoO6, which is expected to
have complete spin polarization, however all samples present some degree of Fe/Mo disorder
which reduces the tunneling magnetoresistance in granular samples. We consider an
electronic model within the renormalized perturbation expansion Green’s functions,
consisting in a correlated electron picture with localized Fe-ions and itinerant electrons
interacting with the local spins via a double-exchange type mechanism. Our results show
the influence of disorder on the density of states and the ground-state properties,
particularly on the spin polarization over the whole range of x. 相似文献
17.
A. A. Mukhin V. Yu. Ivanov V. D. Travkin S. P. Lebedev A. Pimenov A. Loidl A. M. Balbashov 《JETP Letters》1998,68(4):356-362
The electrical conductivity, magnetic susceptibility, magnetization, and submillimeter (v=5∓20 cm−1) permittivity and dynamic conductivity of La1−x
Sr
x
MnO3 (0≤x≤ 0.45) single crystals are investigated. The anomalies in the temperature dependences of these quantities are identified
with diverse magnetic and structural phase transformations, including antiferromagnetic and ferromagnetic ordering, structural
transitions between strongly distorted (Jahn-Teller) and weakly distorted (pseudocubic) orthorhombic phases, structural transitions
to a rhombohedral phase and unusual transitions to a polaron-ordering state. As a result, the complete T-x phase diagram of the system La1−2x
Sr
x
MnO3 is constructed in a wide interval of temperatures T=4.2∓1050 K and concentrations x=0−0.45.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 331–336 (25 August 1998) 相似文献
18.
Manganese-doped ZnSiAs<Subscript>2</Subscript> chalcopyrite: A new advanced material for spintronics
L.?I.?Koroleva D.?M.?Zashchirinski? T.?M.?Khapaeva S.?F.?Marenkin I.?V.?Fedorchenko R.?Szymczak B.?Krzumanska V.?Dobrovol’ski? L.?Kilanski? 《Physics of the Solid State》2009,51(2):303-308
A new spintronics material with the Curie temperature above room temperature, the ZnSiAs2 chalcopyrite doped with 1 and 2 wt % Mn, is synthesized. The magnetization, electrical resistivity, magnetoresistance, and
the Hall effect of these compositions are studied. The temperature dependence of the electrical resistivity follows a semiconducting
pattern with an activation energy of 0.12–0.38 eV (in the temperature range 124 K ≤ T ≤ 263 K for both compositions). The hole mobility and concentration are 1.33, 2.13 cm2/V s and 2.2 × 1016, 8 × 1016 cm−3 at T = 293 K for the 1 and 2 wt % Mn compositions, respectively. The magnetoresistance of both compositions, including the region
of the Curie point, does not exceed 0.4%. The temperature dependence of the magnetization M(T) of both compositions exhibits a complicated character; indeed, for T ≤ 15 K, it is characteristic of superparamagnets, while for T > 15 K, spontaneous magnetization appears which correspond to a decreased magnetic moment per formula unit as compared to
that which would be observed upon complete ferromagnetic ordering of Mn2+ spins or antiferromagnetic ordering of spins of the Mn2+ and Mn3+ ions. Thus, for T > 15 K, it is a frustrated ferro- or ferrimagnet. It is found that, unlike the conventional superparamagnets, the cluster
moment μ
c
in these compositions depends on the magnetic field: ∼12000–20000μB for H = 0.1 kOe, ∼52–55μB for H = 11 kOe, and ∼8.6–11.0μB at H = 50 kOe for the compositions with 1 and 2 wt % Mn, respectively. The specific features of the magnetic properties are explained
by the competition between the carrier-mediated exchange and superexchange interactions. 相似文献
19.
A. G. Gamzatov A. M. Aliev K. Sh. Khizriev I. K. Kamilov A. S. Mankevich I. E. Korsakov 《Physics of the Solid State》2011,53(11):2271-2274
The heat capacity of the manganite La0.87K0.13MnO3 has been measured in the temperature range 80–350 K. The nature of the ferromagnetic phase transition and the critical properties
of heat capacity near the Curie temperature have been studied. The regularities of variations in the universal critical parameters
near the phase transition point have been established. The calculated critical exponent and amplitudes of the heat capacity
with allowance for corrections on the scaling (α = −0.13 and A
+/A
− = 1.178) correspond to the critical behavior of the 3D Heizenberg model. 相似文献
20.
E. D. Politova B. V. Egorova G. M. Kaleva A. V. Mosunov S. Yu. Stefanovich A. G. Segalla J. Zeng 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(8):1166-1169
The ferroelectric and piezoelectric properties of ceramic solid solutions having a composition of (1−x)(Bi0.9Nd0.1)(Sc0.9
B
0.1)O3 − x
PbTiO3 (x = 0.60–0.66; B = Lu, Yb, Er, Y) and obtained by solid state reaction were studied. An increase in the Curie temperature was found upon an
increase in the concentration of lead titanate, while a drop occured upon the doping of the A and B sublattices. It was shown that at high temperatures, MnO2 and Bi2O3 additives lead to a reduction in the total conductivity and a dielectric loss of less than one order of magnitude. In modified
ceramics, an increase in the d
33 and k
t piezoelectric coefficients was observed as well. The effects of dielectric relaxation that are determined by the composition
of the ceramics were revealed. 相似文献