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1.
This paper discusses the pulsed electron conductivity σ of KCl, KBr, and NaCl crystals when they are excited by an electron beam (0.2 MeV, 50 ps) with current densities in the interval
j=(30–104) A/cm2. It is shown that the lifetime of the electrons in the conduction band is τ≪100 ps. To explain the experimental σ(j) dependences, a model is proposed that includes electron capture by structural defects and stable radiation defects at low
excitation densities and electron capture predominantly by unstable radiation defects generated by the excitation pulse at
high excitation densities.
Fiz. Tverd. Tela (St. Petersburg) 41, 1200–1203 (July 1999) 相似文献
2.
The pulsed conductivity is investigated for a CsI-Tl crystal having a Tl+ concentration N=8×1017cm−3 and excited by an electron beam (0.2 MeV, 50 ps, 102–104
A/cm
2). It is shown that the amplitude of the conduction current pulse is almost an order of magnitude lower than for “pure” CsI
crystals irradiated under like conditions. The conduction current relaxation time is preserved up to τ=100 ps in this case. Under the experimental conditions, therefore, the lifetime of electrons in the conduction band is controlled
by trapping at Tl+ centers. The electron capture cross section at a Tl+ center is determined: σ=7×10−16 cm2, which agrees in order of magnitude with estimates of the capture cross section for a neutral trapping center.
Fiz. Tverd. Tela (St. Petersburg) 40, 66–67 (January 1998) 相似文献
3.
The results of investigating of the thermal conducitivity of a GaS single crystal in directions parallel and perpendicular
to the c axis in the temperature interval 5–300 K are reported. The investigations show that the degree of anisotropy of the thermal
conductivity of GaS decreases with temperature.
Fiz. Tverd. Tela (St. Petersburg) 41, 24–25 (January 1999) 相似文献
4.
Experimental data on the thermal conductivity K(T) of natural and highly enriched (99.99%) Ge70 crystals with ground and polished surfaces are analyzed in the temperature interval ∼2–8 K. In all samples, the boundary
scattering mechanism predominates in the interval from 2 to 4.0 K. As temperature increases, in highly enriched samples N processes start to contribute to phonon transport and the behavior of K(T) corresponds to viscous Poiseuille flow of a phonon gas. The isotopic scattering mechanism plays a large role in isotopically
nonideal samples.
Fiz. Tverd. Tela (St. Petersburg) 40, 1604–1607 (September 1998) 相似文献
5.
L. S. Parfen’eva T. S. Orlova N. F. Kartenko N. V. Sharenkova B. I. Smirnov I. A. Smirnov H. Misiorek A. Jezowski T. E. Wilkes K. T. Faber 《Physics of the Solid State》2010,52(6):1115-1122
This paper reports on measurements performed in the temperature range 5–300 K for the thermal conductivity κ and electrical
resistivity ρ of high-porosity (cellular pores) biocarbon preforms prepared by pyrolysis (carbonization) of beech wood in
an argon flow at carbonization temperatures of 1000 and 2400°C. X-ray structure analysis of the samples has been performed
at 300 K. The samples have revealed the presence of nanocrystallites making up the carbon matrices of these biocarbon preforms.
Their size has been determined. For samples prepared at T
carb = 1000 and 2400°C, the nanocrystallite sizes are found to be in the ranges 12–25 and 28–60 κ(T) are determined for the samples cut along and across the tree growth direction. The thermal conductivity κ increases with
increasing carbonization temperature and nanocrystallite size in the carbon matrix of the sample. Thermal conductivity measurements
conducted on samples of both types have revealed an unusual temperature dependence of the phonon thermal conductivity for
amorphous materials. As the temperature increases from 5 to 300 K, it first increases in proportion to T, to transfer subsequently to ∼T
1.5 scaling. The results obtained are analyzed. 相似文献
6.
Results are presented from the first stage of studies on the passage of an electron beam with energy 100–500 eV in a magnetic
field of 300–700 Oe through the curvilinear solenoid of the KRéL unit, the latter being a prototype of the closing segment
of the Drakon stellarator system, in the plasma-beam discharge regime. The ion density at the end of the curvilinear part
of the chamber, n
i
≈8×108–1010 cm−3, the electron temperature T
e
≈4–15 eV, and the positions at which the beam hits the target for different distances from it to the electron source are determined
experimentally. The motion of the electron beam is computationally modeled with allowance for the space charge created by
the beam and the secondary plasma. From a comparison of the experimentally measured trajectories and trajectories calculated
for different values of the space charge, we have obtained an estimate for the unneutralized ion density of the order of 5×107 cm−3.
Zh. Tekh. Fiz. 69, 22–26 (February 1999) 相似文献
7.
V. A. Kul’bachinskii V. G. Kytin R. A. Lunin A. V. Golikov A. V. Demin A. S. Bugaev A. P. Senichkin A. De Visser R. T. F. Van Schaijk 《Journal of Experimental and Theoretical Physics》1999,89(6):1154-1159
The effect of illumination with various wavelengths λ (770 nm<λ<1120 nm) on the conductivity of GaAs structures with tin δ-doping of the vicinal faces was investigated in the temperature range 4.2–300 K. Negative persistent photoconductivity was
found in strongly doped samples. It was shown on the basis of the results of investigations of the Hall and Shubnikov-de Haas
effects that the negative photoconductivity is due to a large decrease in the electron mobility with increasing electron density.
The decrease of electron mobility is explained by ionization of DX centers, which destroys the spatial correlation in the
distribution of positively charged donors and negatively charged DX centers.
Zh. éksp. Teor. Fiz. 116, 2130–2139 (December 1999) 相似文献
8.
A. V. Golubkov L. S. Parfen'eva I. A. Smirnov H. Misiorek J. Mucha A. Jezowski 《Physics of the Solid State》1999,41(1):22-24
Measurement of the heat conductivity and electrical resistivity of two Sm1−x
GdxS compositions with x=0.1 and 0.14 is reported within the 80–300 K interval. An analysis of experimental data on the electronic component of heat
conductivity permits a conclusion that the d subband of “heavy” carriers in the conduction band of these materials lies above the s “light”-carrier subband.
Fiz. Tverd. Tela (St. Petersburg) 41, 26–29 (January 1999) 相似文献
9.
Sh. M. Ismailov N. L. Kramynina N. V. Lugueva 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(8):1169-1171
The effect of temperature and pressure on heat conductivity of ternary compounds TiSbC
2VI (C
VI → S, Se, Te) in the solid and liquid states in a temperature range of 300–800 K, as well as under the pressure up to 0.35
GPa in a temperature range of 275–450 K, is studied. The dependence of heat conductivity on average atomic weight under the
S → Se → Te transition is found. Analysis of the experimental data makes it possible to attribute TlSbS2 to the class of substances exhibiting semiconductor-semiconductor melting behavior. 相似文献
10.
T. V. Panchenko 《Physics of the Solid State》1997,39(7):1085-1090
Anomalies of the dielectric properties of undoped and aluminum-and gallium-doped crystals of Bi12SiO20 are investigated in the frequency and temperature range ν=102–108 Hz and T=300–800 K. They are shown to be due to Debye relaxation processes and determined by the relaxor parameters. The mechanism
of electron thermal polarization is discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 1223–1229 (July 1997) 相似文献
11.
N. I. Sorokin M. V. Fominykh E. A. Krivandina Z. I. Zhmurova B. P. Sobolev O. I. Lyamina 《Physics of the Solid State》1998,40(4):604-607
The fluoride-ion conductivity of the nonstoichiometric tysonite phases La0.95(Ba1−x
Srx)0.05Fe2.95 (0⩽x⩽1) is investigated by impedance spectroscopy. Electrophysical measurements are performed in the frequency range 5–5×105 Hz and temperature range 300–700 K. A discontinuity is observed in the temperature dependence of the conductivity at T
c=410–430 K. The behavior of the temperature dependence of the electrical conductivity is explained within a transport model
taking into account the migration of fluoride ions between different inequivalent structural sites. The maximum value of the
conductivity at room temperature (293 K) is 2×10−4 Ω−1 cm−1 for the solid solution La0.95Sr0.05F2.95. The fluorine-ion conductivity in La0.95(Ba1−x
Srx)0.05F2.95 single crystals is almost an order of magnitude larger than the value for the commercial solid electrolyte La0.992Eu0.008F2.992 (a fluorine-selective membrane) having a tysonite structure.
Fiz. Tverd. Tela (St. Petersburg) 40, 658–661 (April 1998) 相似文献
12.
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
13.
A. G. Lipson B. F. Lyakov D. M. Sakov V. A. Kuznetsov 《Physics of the Solid State》1997,39(12):1891-1894
An increase has been found in the electrical conductivity of electrochemically dehydrogenated palladium hydrides (deuterides)
as compared with original samples of pure palladium in a wide temperature range (75–300 K). It is shown that this effect is
due to the suppression of the scattering of conduction electrons by phonons in the palladium lattice for T⩾θ (θ is the Debye temperature) in the presence of clusters of quasimetallic hydrogen (deuterium).
Fiz. Tverd. Tela (St. Petersburg) 39, 2113–2117 (December 1997) 相似文献
14.
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
15.
V. I. Tsebro O. E. Omel’yanovskii E. F. Kukovitskii N. A. Sainov N. A. Kiselev D. N. Zakharov 《Journal of Experimental and Theoretical Physics》1998,86(6):1216-1219
Bulk samples of carbon multilayer nanotubes with the structure of nested cones (fishbone structure) suitable for transport
measurements, were prepared by compressing under high pressure (∼25 kbar) a nanotube precursor synthesized through thermal
decomposition of polyethylene catalyzed by nickel. The structure of the initial nanotube material was studied using high-resolution
transmission electron microscopy. In the low-temperature range (4.2–100 K) the electric resistance of the samples changes
according to the law ln R ∝ (T
0/T)1/3, where T
0∼7 K. The measured magnetoresistance is quadratic in the magnetic field and linear in the reciprocal temperature. The measurements
have been interpreted in terms of two-dimensional variable-range hopping conductivity. It is suggested that the space between
the inside and outside walls of nanotubes acts as a two-dimensional conducting medium. Estimates suggest a high value of the
density of electron states at the Fermi level of about 5×1021 eV−1 cm−3.
Zh. éksp. Teor. Fiz. 113, 2221–2228 (June 1998) 相似文献
16.
A. A. Verevkin N. G. Ptitsina K. V. Smirnov G. N. Gol’tsman E. M. Gershenzon K. S. Ingvesson 《JETP Letters》1996,64(5):404-409
The temperature dependence of the energy relaxation time τe (T) of a two-dimensional electron gas at an AlGaAs/GaAs heterointerface is measured under quasiequilibrium conditions in the
region of the transition from scattering by acoustic phonons to scattering with the participation of optical phonons. The
temperature interval of constant τe, where scattering by the deformation potential predominates, is determined. In the preceding, low-temperature region, where
piezoacoustic and deformation-potential-induced scattering processes coexist, τ e decreases slowly with increasing temperature. Optical phonons start to participate in the scattering processes at T∼25 K (the characteristic phonon lifetime was equal to τLOτ4.5 ps). The energy losses calculated from the τe data in a model with an effective nonequilibrium electron temperature agree with the published data obtained under strong
heating conditions.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 5, 371–375 (10 September 1996) 相似文献
17.
Investigations of magnetic susceptibility (χ) of (3HgS)1–x
(Al2S3)
x
(x = 0.5) crystals doped with manganese investigated by the Faraday method in the range of Т = 77–300 K and Н = 0.25–4 kOe demonstrate that peculiar magnetic properties can be due to the presence of clusters of the Mn–S–Mn–S type in
these crystals. Based on the investigation of kinetic coefficients of the crystals performed for Т = 77–300 K and Н = 0.5–5 kOe, it is established that the crystals demonstrate conductivity of the n-type, and their electric conduction only
very slightly depends on the temperature and shows a maximum, the Hall coefficient is independent of the temperature, while
the temperature dependences of mobility exhibit a maximum. Using the concentration dependence of the effective electron mass
at the Fermi level, the width of the forbidden band, the matrix element of interatomic interaction, and the effective mass
on the conduction-band bottom are obtained. Based on investigations by optical methods, the presence of direct optical interband
transitions in the crystals is established and the value of the optical forbidden band (at Т = 300 K) is determined. 相似文献
18.
A. A. Samokhvalov T. I. Arbuzova N. A. Viglin V. V. Osipov N. I. Solin S. V. Naumov V. G. Bamburov N. I. Lobachevskaya O. G. Reznitskikh 《Physics of the Solid State》1999,41(2):262-264
Mg1−x
CuxO solid solutions having an NaCl structure with 0⩽x⩽0.20 are synthesized and Cu-Mg1−x
CuxO structures are prepared for superconductivity studies. The magnetic susceptibility χ, electron paramagnetic resonance (EPR), and electrical conductivity of the solid solutions are studied at temperatures of
5–550 K. It is shown that χ
−1(T) obeys the Curie-Weiss law with a paramagnetic Curie temperature Θ close to zero and an effective magnetic moment μ
eff=1.9 μ
B, close to the 1.73 μ
B of a Cu2+ ion with spin S=1/2. The width ΔH of the EPR line depends weakly on temperature and increases as x is raised. The volume narrowing of the EPR linewidth ΔH is used to estimate the exchange interaction parameter, 3×10−4 eV. The g-factor is close to 2 and is temperature independent. The electrical conductivity of Mg1−x
CuxO at T=300 K is ≈10−11–10−12 Ω−1 cm−1 for x=0 and increases to 10−5–10−6 Ω−1 cm−1 for x=0.15–0.20. The conductivity is p-type. Magnetic shielding is observed in Cu-Mg1−x
CuxO structures with x=0.15 and 0.20. The possible connection of this phenomenon with interference superconductivity in the contact layer of the
structure is discussed.
Fiz. Tverd. Tela (St. Petersburg) 41, 293–296 (February 1999) 相似文献
19.
S. O. Gladkov 《Technical Physics》1999,44(3):291-294
It is predicted that at room temperatures a hopping mechanism of charge transfer plays a very important role and leads to
temperature oscillations of the conductivity σ(T) of a dielectric composite. The dependence of the conductivity σ(ω) on the frequency of an alternating electric field is calculated. The relation obtained can be used to determine, first,
the electron relaxation times and, second, and more importantly, the frequency of electron tunneling through the dielectric
matrix from measurements of the conductivity in various frequency ranges.
Zh. Tekh. Fiz. 69, 31–34 (March 1999) 相似文献
20.
A. N. Vystavkin D. V. Shuvaev L. S. Kuz’min M. A. Tarasov E. Aderstedt M. Willander T. Claeson 《Journal of Experimental and Theoretical Physics》1999,88(3):598-602
This paper describes the design and experimental testing of a high-sensitivity hot-electron bolometer based a film of normal
metal, exploiting the Andreev reflection from superconductor boundaries, and cooled with the help of a superconductor-insulator-normal
metal junction. At the measured thermal conductivity, G≈6×10−12 W/K, and a time constant of τ=0.2 μs, and a temperature of 300 mK, the estimated noise-equivalent power NEP=5×10−18 W/Hz1/2, assuming that temperature fluctuations are the major source of noise. At a temperature of 100 mK, the thermal conductivity
drops to G≈7×10−14 W/K, which yields NEP=2×10−19 W/Hz1/2 at a time constant of τ=5 μs. The microbolometer has been designed to serve as a detector of millimeter and FIR waves in space-based radio telescopes.
Zh. éksp. Teor. Fiz. 115, 1085–1092 (March 1999) 相似文献