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1.
Sheleg A. U. Hurtavy V. G. Shautsova V. V. Aliev V. A. 《Physics of the Solid State》2012,54(3):622-625
This paper reports on a study of the dielectric permittivity and electrical conductivity of single-crystal TlInS
x
Se2 − x
solid solutions as functions of temperature and composition. It has been found that the dielectric permittivity ɛ and electrical
conductivity σ decrease with increasing x and increase with growing temperature. The temperature dependences ɛ = f(T) and σ = f(T) for TlInS
x
Se2 − x
crystals have been demonstrated to reveal anomalies in the form of maxima, which suggests that these crystals undergo phase
transitions. The temperatures of the phase transitions increase with increasing x. 相似文献
2.
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
3.
M. D. Volnyanskii S. N. Plyaka M. P. Trubitsyn Yahia A. H. Obaidat 《Physics of the Solid State》2012,54(3):499-503
The electrical properties of a lithium heptagermanate (Li2Ge7O15) crystal have been studied in DC and AC measuring fields at temperatures from 500 to 700 K. In a DC field, a substantial
decrease of electrical conductivity σ with time has been detected. On the basis of kinetic dependences σ(t), estimates of the charge carrier diffusion coefficient D have been obtained. In the frequency range 101–105 Hz, the spectra of complex impedance ρ*(f) have been measured. The analysis of diagrams in the complex plane (ρ″–ρ′) has been performed within the equivalent circuit
approach. It has been shown that, in the considered temperature and frequency intervals, the electrical properties of Li2Ge7O15 crystals have been determined by the hopping conduction of interstitial lithium ions A
Li and accumulation of charge carriers near the blocking Pt electrodes. 相似文献
4.
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
5.
V. A. Kulbachinskii V. G. Kytin P. M. Tarasov N. A. Yuzeeva 《Physics of the Solid State》2010,52(9):1830-1835
The effect of Ga doping on the temperature dependences (5 K ≤ T ≤ 300 K) of the Seebeck coefficient α, electrical conductivity σ, thermal conductivity coefficient κ, and thermoelectric
figure of merit Z of p-(Bi0.5Sb0.5)2Te3 single crystals has been investigated. It has been shown that, upon Ga doping, the hole concentration decreases, the Seebeck
coefficient increases, the electrical conductivity decreases, and the thermoelectric figure of merit increases. The observed
variations in the Seebeck coefficient cannot be completely explained by the decrease in the hole concentration and indicate
a noticeable variation in the density of states due to the Ga doping. 相似文献
6.
The effect of gamma irradiation on the dielectric properties and ac conductivity of a TlInS2 single crystal with a layered structure has been investigated in the frequency range from 5 × 104 to 3.5 × 107Hz. It has been shown that gamma irradiation of the TlInS2 single crystal with a dose of 104–2.25 × 106 rad leads to a considerable increase in the dielectric loss tangent tanδ, the real part ɛ′ and imaginary part ɛ″ of the complex
permittivity, and the ac conductivity σ
ac
across the layers. It has been established that, for all gamma irradiation doses, the TlInS2 single crystal is characterized by the dielectric loss due to electrical conduction up to a frequency of 107 Hz and by the relaxation loss at a higher frequency. Irradiation of the TlInS2 single crystal results in an increase in the dispersion of tan δ, ɛ′, and ɛ″. It has been demonstrated that, as the gamma
irradiation dose is accumulated in the TlInS2 single crystal, the density of localized states near the Fermi level N
F increases (from 5.2 × 1018 to 1.9 × 1019 eV−1 cm−3). 相似文献
7.
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
8.
V. V. Popov P. P. Konstantinov Yu. V. Rud’ 《Journal of Experimental and Theoretical Physics》2011,113(4):683-691
Electrical resistivity ρ and Hal coefficient R are measured as a function of the temperature (T = 1.7−310 K) and the magnetic field (up to H = 28 kOe) in zero-gap semiconductor CuFeS2 samples subjected to hydrostatic compression and under various heat-treatment conditions. At low temperatures, anomalies
are observed in the kinetic effects related to the presence of ferromagnetic clusters: the magnetoresistance at T = 4.2 K and T = 20.4 K acquires a hysteretic character and thermopower α changes its sign at T < 15 K. The temperature dependence of conduction-electron concentration n in CuFeS2 has a power form in the temperature range T = 14−300 K, which is characteristic of the intrinsic conductivity in zero-gap semiconductors. In CuFeS2, we have n(T) ∝ T
1.2; in isoelectron compound Cu1.13Fe1.22Te2, we have n(T) ∝ T
1.93. Heat treatment is found to affect the intrinsic conductivity of CuFeS2, as the action of hydrostatic compression (carrier concentration changes); that is, the carrier concentration changes. However,
a power form of the n(T) and ρ(T) dependences is retained. 相似文献
9.
S. N. Mustafaeva Sh. G. Gasymov E. M. Kerimova M. M. Asadov 《Physics of the Solid State》2012,54(1):44-47
Pressure and temperature dependences of the conductivity anisotropy of TlGaTe2 chain single crystals have been investigated. It has been found that the conductivity anisotropy of TlGaTe2 can be controlled by choosing the values of temperature and pressure. The temperatures (216, 193, and 77 K) and corresponding
pressures (0, 0.31, and 0.71 GPa) have been determined, at which the conductivity of the TlGaTe2 single crystal becomes isotropic. 相似文献
10.
R. M. Sardarly O. A. Samedov A. P. Abdullaev F. T. Salmanov 《Physics of the Solid State》2011,53(8):1564-1568
The conductivity and temperature-frequency dependences of the permittivity of TlGaTe2 crystals have been studied. Strong dielectric relaxation has been revealed. It has been shown that the mechanism of dielectric
relaxation is associated with hopping of Tl ions over vacancies in the thallium sublattice due to the transition of the system
to the superionic state. 相似文献
11.
Sheleg A. U. Hurtavy V. G. Mustafaeva S. N. Kerimova E. M. Shautsova V. V. 《Physics of the Solid State》2012,54(3):607-610
This paper reports on a study of the electrical conductivity and permittivity of Tl(InS2)
1−x
(FeSe2)
x
crystals as functions of composition and temperature. It has been found that the permittivity decreases in magnitude, while
the electrical conductivity increases with increasing x. Crystals Tl(InS2)
1−x
(FeSe2)
x
have been observed to undergo a sequence of phase transitions characteristic of TlInS2, which manifests itself in formation of anomalies in the σ = f(T) and ɛ = f(T) temperature dependences. It has been shown that as x increases, the phase transition temperatures decrease, while the temperature region within which the incommensurate phase
persists broadens slightly. 相似文献
12.
L. Kovács M. Mazzera E. Beregi R. Capelletti 《Applied physics. B, Lasers and optics》2009,94(2):273-277
Several weak absorption bands have been observed in the optical absorption spectra of pure and rare-earth-doped YAl3(BO3)4 single crystals in the 3350– 3650 cm−1 wave number region. Two of them, peaking at about 3377 cm−1 and 3580 cm−1 in the 8 K spectra, appear in most of the samples. They are tentatively attributed to the stretching mode of OH− ions incorporated in the crystal during the growth. An additional absorption band at about 5250 cm−1 at 8 K has also been detected in almost all samples. The temperature and polarization dependences of these bands, and their
possible origin, are discussed. 相似文献
13.
M.?P.?Ivliev S.?I.?Raevskaya O.?Yu.?Kravchenko I.?P.?Raevski? L.?A.?Reznichenko 《Physics of the Solid State》2009,51(10):2109-2114
It is established that the Curie-Weiss temperature of Na1 − x
Li
x
NbO3 solid solutions determined by extrapolation of linear portions of the temperature dependence of the reciprocal of the permittivity
ɛ−1 from the cubic phase sharply increases with x, although the temperature of the ɛ(T) maximum decreases. It is shown in terms of a simple theoretical model that the experimentally observed change in the dielectric
properties of Na1 − x
Li
x
NbO3 is well explained under the assumption of formation of a dipole system due to the displacement of Li cations from the center
of the cubooctahedral cavity because of the significant steric misfit between the Na and Li cations. 相似文献
14.
The temperature behavior of I-U curves and the field and temperature dependences of the electrical resistivity and dielectric permittivity of crystals of the LiCu2O2 phase have been studied. It was established that the crystals belong to p-type semiconductors and that their static resistivity in the range 80–260 K follows the Mott law ρ=Aexp(T0/T)1/4 describing variable-range hopping over localized states. At comparatively low electric fields, the crystals exhibit threshold switching and characteristic S-shaped I-U curves containing a region of negative differential resistivity. In the critical voltage region, jumps in the conductivity and dielectric permittivity are observed. Possible mechanisms of the disorder and electrical instability in these crystals are discussed. 相似文献
15.
Spectral dependences of the relative permittivity ɛ = ɛ1 − iɛ2 of a uniaxial weak ferromagnet FeBO3 are measured for two principal polarizations in the energy range 0.6–5.6 eV. The positions have been determined for the charge-transfer
transitions that make the main contribution to absorption above the bandgap and determine the refractive-index dispersion
below the bandgap. The isotropic magnetic contribution to the refractive index has been detected by studying the temperature
dependence of the refractive index in the range 100–700 K; its value (≈2 × 10−2) is found to be record high for magnetic dielectrics. The energy shift of the effective oscillator, which characterizes the
shift of the positions of the charge-transfer transitions due to magnetic ordering, is determined from these data within the
framework of a single-oscillator model. The value of the exchange striction in FeBO3 is determined from optical measurements. 相似文献
16.
H.-F. Li Y. Su Tapan Chatterji A. Nefedov J. Persson P. Meuffels Y. Xiao D. Vaknin Th. Brückel 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(4):457-461
Soft X-ray resonant scattering studies at the Mn LII, III- and the La MIV, V- edges of single-crystal LaSr2Mn2O7 are
reported. At low temperatures, below TN ≈ 160 K, energy scans with a fixed momentum transfer at the A-type antiferromagnetic (0 0
1) reflection around the Mn LII, III-edges with incident linear σ and π polarizations show strong resonant enhancements. The
splitting of the energy spectra around the Mn LII, III-edges may indicate the presence of a mixed valence state, e.g., Mn3+/Mn4+.
The relative intensities of the resonance and the clear shoulder-feature as well as the strong incident σ and π polarization
dependences
strongly indicate its complex electronic origin. Unexpected enhancement of the charge Bragg (0 0 2) reflection at the La MIV, V-edges with
σ polarization has been observed up to 300 K, with an anomaly appearing around the orbital-ordering transition temperature,
TOO ≈
220 K, suggesting a strong coupling (competition) between them. 相似文献
17.
18.
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
19.
G. A. Komandin A. S. Prokhorov V. I. Torgashev E. S. Zhukova B. P. Gorshunov A. A. Bush 《Physics of the Solid State》2011,53(4):736-744
The spectra of complex permittivity of a Ba2Mg2Fe12O22 single crystal belonging to the family of Y-type hexaferrites have been measured over a wide temperature range (10–300 K) with the aim of determining the dynamic parameters
of the phonon and magnetic subsystems in the terahertz and infrared frequency ranges (3–4500 cm−1). A factor-group analysis of the vibrational modes has been performed, and the results obtained have been compared with the
experimentally observed resonances. The oscillator parameters of all nineteen phonon modes of E
u
symmetry, which are allowed by the symmetry of the Ba2Mg2Fe12O22 crystal lattice, have been calculated. It has been found that, at temperatures below 195 and 50 K, the spectral response
exhibits new absorption lines due to magnetic excitations. 相似文献
20.
We have studied photoluminescence and thermoluminescence (PL and TL) in CaGa2Se4:Eu crystals in the temperature range 77–400 K. We have established that broadband photoluminescence with maximum at 571 nm
is due to intracenter transitions 4f6 5d–4f7 (8S7/2) of the Eu2+ ions. From the temperature dependence of the intensity (log I–103/T), we determined the activation energy (E
a = 0.04 eV) for thermal quenching of photoluminescence. From the thermoluminescence spectra, we determined the trap depths:
0.31, 0.44, 0.53, 0.59 eV. The lifetime of the excited state 4f6 5d of the Eu2+ ions in the CaGa2Se4 crystal found from the luminescence decay kinetics is 3.8 μsec.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 112–116, January–February, 2009. 相似文献