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1.
Chen Li-chuan A. Rabenau W. Weppner 《Applied Physics A: Materials Science & Processing》1978,17(3):233-237
The ionic and electronic conductivities of Ag2Tl6I10 single crystals have been studied as a function of crystallographic orientation and temperature from 20 to 135°C. EMF as
well as AC and DC techniques have been employed. The highly anisotropic material is predominantly an Ag+-ion conductor parallel toc-direction, with the Ag+ ions moving through linear channels that are not interconnected. The conductivity σ‖c
=1.6×10−7Ω−1cm−1 at 25°C, with an activation enthalpy for σ‖c
of 0.38 eV. The conduction perpendicular toc-direction has been found to be predominantly electronic with a value of σ⊥c
=3×10−9Ω−1cm−1 at 25°C and an activation enthalpy for σ⊥c
of 0.64 eV. This is the first observation of one-dimensional Ag+ conduction and this type of orientation-dependent change from ionic to electronic conduction.
On leave from Institute of Physics, Academia Sinica, Peking, China. 相似文献
2.
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
3.
V S K Balagurusamy S Krishna Prasad S Chandrasekhar Sandeep Kumar M Manickam C V Yelamaggad 《Pramana》1999,53(1):3-11
We have studied the electrical conductivity of well aligned samples of hexahexylthiotriphenylene (HHTT) in the pure as well
as doped states. The dopant used was a small concentration (0.62 mole %) of the electron acceptor trinitrofluorenone (TNF).
In the columnar phases, doping causes the AC(1 kHz) conductivity along the columnar axis (σ
‖) to increase by a factor of 107 or more relative to that in undoped samples; σ
‖ attains a value of 10−2S/m, which was the maximum measurable limit of our experimental set up. On the other hand, in the isotropic phase doping makes
hardly any difference to the conductivity. The frequency dependence of the conductivity has been investigated. The DC conductivity
of doped samples exhibits an enormous anisotropy, σ
‖/σ
⊥ ≥ 1010, which is 7 orders higher than that reported for any liquid crystalline system, and, to our knowledge, the largest observed
in an organic conductor.
We also report the first thermoelectric power studies on these ‘molecular wires’. The sign of the thermoelectric power is
in conformity with the expected nature of the charge carriers, namely, holes. 相似文献
4.
The anisotropy of electrical conductivity in hexagonal TlInS2 crystals irradiated by γ-quanta is investigated. It is established that irradiation by low doses (~50 krad) gives rise to
accumulation of radiation defects both in the tetrahedral space and in the layer plane. As a result, there is an increase
in electrical conductivities σ⊥C and σ∥C. As the dose is increased (above 200 krad), more complex defects are formed due to interaction of the radiation defects with
the inhomogeneities, thus reducing the increase of electrical conductivity in both directions. 相似文献
5.
V. A. Shklovskii A. K. Soroka A. A. Soroka 《Journal of Experimental and Theoretical Physics》1999,89(6):1138-1153
The nonlinear resistive properties of superconductors in the mixed state in the presence of a system of unidirectional planar
defects (twins) have been investigated theoretically within the framework of the two-dimensional stochastic model of anisotropic
pinning based on the Fokker-Planck equations with a concrete form of the pinning potential. These equations allow one to obtain
an exact analytical solution of the problem. Formulas are obtained for experimentally observable even and odd (relative to
reversal of the direction of the external magnetic field) nonlinear longitudinal and transverse magnetoresistivities ρ
‖,⊥
±
( j,t,α,ε) as functions of the transport current density j, temperature t, the angle α between the directions of the current and the twins, and the relative volume fraction ε occupied by the twins. In light of the great variety of types of nonlinear resistive dependences contained in these expressions
for ρ
‖,⊥
±
the most characteristic of them are presented in the form of graphs with commentary. The desired nonlinear dependences ρ
‖,⊥
±
are linear combinations of the even and odd parts of the function v(j,t, α,ε), which has the sense of the probability of overcoming the potential barrier of the twins; this makes it possible to give
a simple physical treatment of the nonlinear regimes. New scaling relations for the Hall conductivity are obtained and investigated
which differ from the previously known relations for isotropic pinning. The interaction of vortex motion directed along the
twins and the Hall effect is considered for Hall constants which are arbitrary in magnitude and sign, and it is shown that
in the case of small Hall viscosity vortex motion directed along the twins has an effect on the odd magnetoresistivities ρ
‖
−
and ρ
⊥
−
, whereas the reverse effect can be neglected. It is shown that pinning anisotropy is sufficient to manifest the new nonlinear
(in the current) magnetoresistivities ρ
⊥
+
and ρ
‖
−
.
Zh. éksp. Teor. Fiz. 116, 2103–2129 (December 1999) 相似文献
6.
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
7.
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
8.
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
9.
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
10.
L. K. Aminov A. A. Ershova V. N. Efimov S. L. Korableva I. N. Kurkin B. Z. Malkin A. A. Rodionov 《Physics of the Solid State》2010,52(10):2070-2075
The EPR spectra of Ce3+ impurity ions in LiYF4, LiLuF4, and LiTmF4 double-fluoride single crystals have been investigated at a frequency of ∼9.3 GHz in the temperature range 5–25 K. The effective
g factors of the ground Kramers doublet of the cerium ions in three crystals are close to each other (g
‖ = 2.737, g
⊥ = 1.475 for LiYF4:Ce3+). A superhyperfine structure of the EPR spectrum of Ce3+ ions in the LiTmF4 Van Vleck paramagnet has been observed in the external magnetic field B oriented along the crystallographic axis c (B ‖ c). The superhyperfine structure of the EPR soectra of the Ce3+ ions in the LiYF4 and LiLuF4 diamagnetic matrices is resolved for B ⊥ c. Possible factors responsible for this pronounced difference in the properties of the systems studied have been discussed. 相似文献
11.
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
12.
The Ac electrical conductivity and the dielectric relaxation properties of the [(C3H7)4N]2Cd2Cl6 polycrystalline sample have been investigated by means of impedance spectroscopy measurements over a wide range of frequencies
and temperatures, 209 Hz–5 MHz and 361–418 K, respectively. The purpose is to make a difference between the electrical and
dielectric properties of the polycrystalline sample and single crystal. Besides, a detailed analysis of the impedance spectrum
suggests that the electrical properties of the material are strongly temperature-dependent. Plots of (Z" versus Z') are well
fitted to an equivalent circuit model consisting of a series combination of grains and grains boundary elements. Moreover,
the temperature dependence of the electrical conductivity in the different phases follows the Arrhenius law and the frequency
dependence of σ (ω) follows the Jonscher’s universal dynamic law. Furthermore, the modulus plots can be characterized by full
width at half height or in terms of a nonexperiential decay function φ(t) = exp(t/t)β. Finally, the imaginary part of the permittivity constant is analyzed with the Cole–Cole formalism. 相似文献
13.
A. M. Kuz’menko A. A. Mukhin V. Yu. Ivanov A. M. Kadomtseva L. N. Bezmaternykh 《JETP Letters》2011,94(4):294-300
Resonance modes that are due to magnetic excitations in the exchange-coupled subsystems of rare-earth ions (R = Nd3+, Sm3+, and Gd3+) and Fe3+ ions have been detected in submillimeter transmission spectra (0.1–0.6 THz) of RFe3(BO3)4 iron borate-multiferroic single crystals. The strong interaction between spin oscillations of the Fe and R subsystems has
been revealed, which determines the behavior of the modes depending on the anisotropy of the exchange splitting of the ground
doublet of the R ion. It has been shown that the intensities of coupled modes (contributions to the magnetic permeability)
depend strongly on the difference between the g factors of Fe and R ions. This dependence makes it possible to determine the sign of the latter g factor. In particular, a noticeable intensity of exchange Nd modes in NdFe3(BO3)4 is due to an increase in their contribution at g
⊥, ‖Nd < 0, while in GdFe3(BO3)4 with g
Gd ≈ g
Fe ≈ 2, the Fe and Gd contributions compensate each other and the exchange (Gd) mode is not observed. In spite of the weak interaction
of Sm ions with the magnetic field, SmFe3(BO3)4 exhibits resonance modes, which are attributed to the excitation of Sm ions through the Fe subsystem. 相似文献
14.
Single crystals of gadolinium orthosilicate Gd2SiO5 containing 0.5 at% and 5 at% of Sm3+ were grown by the Czochralski method. Optical absorption spectra, luminescence spectra and luminescence decay curves were
recorded for these systems at 10 K and at room temperature. Comparison of optical spectra recorded in polarized light revealed
that the anisotropy of this optically biaxial host affects the intensity distribution within absorption and emission bands
related to transitions between multiplets rather than the overall band intensity. It has been found that among four bands
of luminescence related to the 4G5/2→6HJ (J=5/2–11/2) transitions of Sm3+ in the visible and near infrared region the 4G5/2 →6H7/2 one has the highest intensity with a peak emission cross section of 3.54×10−21 cm2 at 601 nm for light polarized parallel to the crystallographic axis c of the crystal. The luminescence decay curve recorded
for Gd2SiO5:0.5 at% Sm3+ follows a single exponential time dependence with a lifetime 1.74 ms, in good agreement with the 4G5/2 radiative lifetime τ
rad=1.78 ms calculated in the framework of Judd-Ofelt theory. Considerably faster and non-exponential luminescence decay recorded
for Gd2SiO5:5 at% Sm3+ sample was fitted to that predicted by the Inokuti-Hirayama theory yielding the microparameter of Sm3+–Sm3+ energy transfer C
da=1.264×10−52 cm6×s−1. 相似文献
15.
The ionic conductivity of PVC–ENR–LiClO4 (PVC, polyvinyl chloride; ENR, epoxidized natural rubber) as a function of LiClO4 concentration, ENR concentration, temperature, and radiation dose of electron beam cross-linking has been studied. The electrolyte
samples were prepared by solution casting technique. Their ionic conductivities were measured using the impedance spectroscopy
technique. It was observed that the relationship between the concentration of salt, as well as temperature, and conductivity
were linear. The electrolyte conductivity increases with ENR concentration. This relationship was discussed using the number
of charge carrier theory. The conductivity–temperature behaviour of the electrolyte is Arrhenian. The conductivity also varies
with the radiation dose of the electron beam cross-linking. The highest room temperature conductivity of the electrolyte of
8.5 × 10−7 S/cm was obtained at 30% by weight of LiClO4. The activation energy, E
a and pre-exponential factor, σ
o, are 1.4 × 10−2 eV and 1.5 × 10−11 S/cm, respectively. 相似文献
16.
M. Ganesan 《Ionics》2007,13(5):379-385
Lithium lanthanoid silicates are projected as promising solid electrolytes for solid-state high-temperature lithium batteries.
Synthesis of Li1−x
Sm1+x
SiO4 (x = 0.2 to 0.6) was carried using sol–gel method, and these compounds were characterized by thermogravimetry differential thermal
analysis, X-ray diffraction, Fourier transform infrared, and SEM. Impedance measurements were carried out at different temperatures,
and conductivity at different temperatures was calculated. The effect of an increase of samarium content on the conductivity
of the solid electrolyte was studied in this paper. It was found that less samarium content exhibits good conductivity at
higher temperatures. 相似文献
17.
K. P. Andryushin A. A. Pavelko I. A. Verbenko O. N. Razumovskaya L. A. Shilkina V. A. Aleshin L. A. Reznichenko 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(8):1082-1084
Ceramic samples of bismuth ferrite and solid solutions of Bi1 − x
A
x
FeO3 type (where A = Lu, Yb, Tm, Er, Ho, Dy, Tb, Gb, Eu, Sm, Nd, Pr, La; 0.05 ≤ x ≤ 0.20; Δx = 0.05) were prepared. Spectra of the real part of electrical conductivity were studied within the range 10−4–10−6 Hz. The dependence of the samples’ thermal stability and electrical conductivity on the size of the substituting ions was
established. 相似文献
18.
Boltzmann-transport equation is analytically solved for two-component magnetoplasma using Chapman-Enskog analysis to include
collisional diffusion transport having anisotropies in both streaming velocity and temperature components. The modified collisional
integrals are analytically solved with flux integrals and perturbed kinetic equation to arrive at drift diffusion velocity
and resulting transport coefficients which are markedly affected by both streaming and temperature anisotropy. The early isotropic
results are recovered in the limit V
0 = 0 and T
‖ = T
⊥ which reduce to eqs (11.30) and (11.31) of [1] and eqs (2.7) and (2.13) of [2]. The electrical resistivity (η⊥) diminishes sharply in fusion temperature limit kT
⊥ = 1 keV. The shape of the curves for both electrical resistivity and thermal conductivity is rectangular hyperbolic. However,
for low thermal ratio (T
‖/T
⊥ < 1), the curves are raised up and for high thermal ratio (T
‖/T
⊥ > 1), they are lowered down the isotropic case (T
‖/T
⊥ > 1), showing comparatively diminished magnitudes of the quantities.
相似文献
19.
The α-Zn2P2O7 compound was obtained by conventional solid-state reaction. The sample was characterized by X-ray powder diffraction, solid
state 31P NMR MAS, and electrical impedance spectroscopy. The solid state 31P MAS NMR, performed at 121.49 MHz, shows three isotropic resonances at −21.1, −18.8, and −15.8 ppm, confirming the non-equivalency
of the three PO4 groups in the α-Zn2P2O7 form. They are characterized by different chemical shift tensor parameters with the local geometrical features of the tetrahedra.
Electrical impedance measurements of β-Zn2P2O7, form stable for temperature greater than 403 K, were performed as a function of both temperature and frequency. The electrical
conduction and dielectric relaxation have been studied. The AC conductivity obeys the universal power law. The approximation
type correlated barrier hopping model explains the universal behavior of the n exponent. The impedance plane plot shows semicircle arcs at different temperatures, and an electrical equivalent circuit
has been proposed to explain the impedance results. The circuits consist of the parallel combination of bulk resistance R
p and constant phase elements CPE. The simulated spectra show a good correlation with the experimental data. 相似文献
20.
I. K. Polushina Yu. V. Rud’ T. N. Ushakova V. Yu. Rud’ 《Physics of the Solid State》1999,41(7):1084-1087
The first results obtained in studies of the temperature dependences of electrical conductivity and Hall constant of n-CdGeAs2 single crystals prepared by low-temperature crystallization are reported. It has been established that the method developed
permits growing single crystals with a free-electron concentration ⋍(1−2)×1018 cm−3 and a Hall mobility ⋍10000 cm2/(Vs) at T=300 K. It is shown that the temperature dependence of Hall mobility exhibits a behavior characteristic of electron scattering
by lattice vibrations, whereas below 150 K a deviation from this law is observed to occur evidencing an increasing contribution
of static lattice defects to scattering. The Hall mobility in the crystals prepared was found to reach ⋍36000 cm2/(Vs) at 77 K. Photosensitive heterojunctions based on n-CdGeAs2 single crystals were prepared. The spectral response of the photosensitivity of these structures is analyzed. It is concluded
that this method is promising for preparation of perfect CdGeAs2 crystals.
Fiz. Tverd. Tela (St. Petersburg) 41, 1190–1193 (July 1999) 相似文献