共查询到20条相似文献,搜索用时 15 毫秒
1.
B. N. Bogomolov N. F. Kartenko D. A. Kurdyukov L. S. Parfen’eva A. A. Sysoeva N. V. Sharenkova I. A. Smirnov H. Miserek J. Mucha A. Jezowski 《Physics of the Solid State》1999,41(2):313-318
Samples of the nanocomposite opal + NaCl with 100% filling of first-order voids in the opal by NaCl have been obtained. The
thermal conductivity of the nanocomposite has been measured in the temperature interval 4.2–300 K. It is shown that NaCl,
introduced into opal, forms a regular “matrix quasilattice” of microcrystals, which leads to suppression of coherent effects
and, as a consequence, of properties characteristic of massive crystals.
Fiz. Tverd. Tela (St. Petersburg) 41, 348–353 (February 1999) 相似文献
2.
A. V. Prokof’ev I. A. Smirnov W. Assmus F. Büllesfeld A. Jezowski 《Physics of the Solid State》1998,40(11):1896-1897
Thermal conductivity ϰ of single-crystal (VO)2P2O7 has been studied within the 4–300 K range. A break was found in the ϰ(T) relation about 200 K, in the region of the transition from diffuse antiferromagnetic ordering (200–4 K) to a classical paramagnet
(T=200–300 K). In the low-temperature domain (4–200 K), one may expect an additional contribution to ϰ(T) from the magnon component of thermal conductivity.
Fiz. Tverd. Tela (St. Petersburg) 40, 2093–2094 (November 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.
L. I. Arutyunyan V. N. Bogomolov N. F. Kartenko D. A. Kurdyukov L. S. Parfen’eva I. A. Smirnov N. V. Sharenkova A. Jezowski J. Mucha H. Misiorek 《Physics of the Solid State》1998,40(2):348-349
An opal-based nanocomposite has been prepared with NaCl incorporated in its pores. The nanocomposite was produced by impregnating
the opal with a NaCl solution at room temperature. Thermal conductivity of the nanocomposite has been measured in the temperature
range 4.2–300 K. The effective heat conductivity of the nanocomposite was found to be equal to that of pure opal. The observed
phenomenon can be explained by assuming that NaCl resides in opal pores in the form of noncontacting needles, thus precluding
heat propagation through it.
Fiz. Tverd. Tela (St. Petersburg) 40, 379–380 (February 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.
O. I. Verba 《Thermophysics and Aeromechanics》2011,18(1):151-154
Thermal conductivity of refrigerant 507A in gaseous state has been measured with a stationary method of coaxial cylinders
in the temperatures range of 315–425 K and pressures 0.105–1.855 MPa. Estimated values of temperature, pressure, and thermal
conductivity measurement errors are, respectively, ± 0.05 K, ± 3.75 kPa and ± 1.5–2.5 %. Approximation dependence for thermal
conductivity in the whole studied temperature and pressure range has been obtained. Results have been compared with available
literature data. 相似文献
7.
V. I. Ozhogin A. V. Inyushkin A. N. Taldenkov A. V. Tikhomirov G. É. Popov E. Haller K. Itoh 《JETP Letters》1996,63(6):490-494
The thermal conductivity of chemically, structurally, and isotopically highly pure germanium single crystals is investigated
experimentally in the temperature range from 2 to 300 K. It is found that the thermal conductivity of germanium enriched to
99.99% 70Ge is 8 times higher at the maximum than the thermal conductivity of germanium with the natural isotopic composition.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 6, 463–467 (25 March 1996) 相似文献
8.
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
9.
The behavior of the thermal conductivity k(T) of bulk faceted fullerite C60 crystals is investigated at temperatures T=8–220 K. The samples are prepared by the gas-transport method from pure C60, containing less than 0.01% impurities. It is found that as the temperature decreases, the thermal conductivity of the crystal
increases, reaches a maximum at T=15–20 K, and drops by a factor of ∼2, proportional to the change in the specific heat, on cooling to 8 K. The effective phonon
mean free path λ
p, estimated from the thermal conductivity and known from the published values of the specific heat of fullerite, is comparable
to the lattice constant of the crystal λ
p∼d=1.4 nm at temperatures T>200 K and reaches values λp∼50d at T<15 K, i.e., the maximum phonon ranges are limited by scattering on defects in the volume of the sample in the simple cubic
phase. In the range T=25−75 K the observed temperature dependence k(T) can be described by the expression k(T)∼exp(Θ/bT), characteristic for the behavior of the thermal conductivity of perfect nonconducting crystals at temperatures below the
Debye temperature Θ (Θ=80 K in fullerite), where umklapp phonon-phonon scattering processes predominate in the volume of the
sample.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 8, 651–656 (25 April 1997) 相似文献
10.
S. N. Ivanov A. V. Taranov E. N. Khazanov E. P. Smirnova 《Journal of Experimental and Theoretical Physics》1999,88(2):342-346
Phonon transport in ferroelectric ceramics and single crystals has been experimentally investigated. Our measurements indicate
that, in the temperature range 1.7–3.8 K studied, the effective phonon diffusion coefficient behaves as D
eff∞T
−5 in ferroelectrics with a broadened phase transition. This experimental dependence is in accord with the presence of a plateau
in the thermal conductivity of such materials. The scattering by domain walls in BaTiO3 single crystals has been identified, and our results are in quantitative agreement with calculations.
Zh. éksp. Teor. Fiz. 115, 624–631 (February 1999) 相似文献
11.
N. N. Sirota V. V. Novikov V. A. Vinokurov Yu. B. Paderno 《Physics of the Solid State》1998,40(11):1856-1858
The temperature dependence of isobaric heat capacity and [411] interplanar spacing in lanthanum and samarium hexaborides have
been determined experimentally within the 5–300 K region. The variation of the lattice parameters and thermal expansion coefficients
α(T) with temperature has been calculated.
Fiz. Tverd. Tela (St. Petersburg) 40, 2051–2053 (November 1998) 相似文献
12.
Thermal conductivity and thermal diffusivity of “ozone-safe” refrigerant R134a in liquid state within the range of temperatures
295.9–354.9 K and pressures from the liquid — vapor equilibrium line up to 4.08 MPa have been studied by high-frequency thermal-wave
method. The experimental uncertainties of the temperature, pressure, thermal conductivity and thermal diffusivity measurement
errors were estimated to be 0.1 K, 3 kPa, 1.5 and 2.5 %, respectively. Values of thermal conductivity and thermal diffusivity
of liquid R134a on saturated line have been calculated. Approximation dependences for thermal conductivity and thermal diffusivity
within the whole studied range of temperatures and pressures as well as on the saturated line have been obtained.
The work was financially supported by the Russian Foundation for Basic Research (grant No. 07-08-00295-a). 相似文献
13.
New generalized formulas for calculation of thermal conductivity of aqueous solutions of binary and multicomponent inorganic
substances under high values of state parameters were derived. New values of thermal conductivity were calculated for aqueous
solutions of salts within the ranges of temperatures of 293–473 K. concentrations of 0–25 mass % and pressures P
s of 100 MPa. 相似文献
14.
I. A. Smirnov L. S. Parfen’eva A. Jezowski H. Misiorek S. Krempel-Hesse F. Ritter W. Assmus 《Physics of the Solid State》1999,41(9):1418-1421
The electrical and thermal conductivities of an YbInCu4 polycrystalline sample have been measured within the 4.2–300-K range. The behavior of the heat conductivity has been found
to change sharply above and below T
v
=70–75 K, the temperature corresponding to an isostructural phase transition from a state with an integral valence (T>T
v
) to a mixed-valence state (T<T
v
) of Yb ions. A preliminary qualitative analysis of the results is presented.
Fiz. Tverd. Tela (St. Petersburg) 41, 1548–1551 (September 1999) 相似文献
15.
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
16.
The temperature dependences of the specific heat and the thermal conductivity of crystalline superionic conductors LnF3 (Ln = La, Ce, Pr), Li2B4O7 and α-LiIO3 in the superionic phase have been investigated experimentally. The specific heat C
p and the thermal conductivity K are observed to increase monotonically over a wide range of temperatures above the Debye temperature ΘD. This increase is attributed to the relaxational interaction of high-frequency phonons with two-level systems.
Fiz. Tverd. Tela (St. Petersburg) 39, 1548–1553 (September 1997) 相似文献
17.
S. A. Shevchenko 《Journal of Experimental and Theoretical Physics》1999,88(1):66-71
Samples of n-type germanium with a donor concentration N
d=2.4×1016 cm−3 are plastically deformed to a degree of strain equal to 18–40% to detect static conduction by electrons trapped on dislocations
in a system of dislocation grids. In samples with 20%<δ<31%, which retain an electronic type of conductivity, the conductivity for T<8 K, which is weakly temperature-dependent, is associated with conduction by electrons trapped on dislocations. The nonmonotonic
dependence of the conductivity at 4.2 K on the degree of strain as the latter increases from 18% to 40% attests to the existence
of an energy gap between the donor and acceptor dislocation states in strongly plastically deformed germanium.
Zh. éksp. Teor. Fiz. 115, 115–125 (January 1999) 相似文献
18.
SrZr1−x
Y
x
O3 coatings were co-sputtered from metallic Zr–Y (84–16 at.%) and Sr targets in the presence of a reactive argon–oxygen gas
mixture. The structural and chemical features of the film have been assessed by X-ray diffraction and scanning electron microscopy.
The electrical properties have been investigated for different substrates by Complex Impedance Spectroscopy as a function
of crystalline state, temperature and atmosphere. The as-deposited coatings are amorphous and crystallise after annealing
at 673 K for 2 h under air. The stabilisation of the perovskite structure is a function of the nominal composition. The films
are dense and present a good adhesion on different substrates. Crystallisation and mechanical stresses are detected by alternating
current (AC) impedance spectroscopy. Significant ionic conductivity in the 473–823 K temperature range is evidenced in air.
Two different conduction regimes in the presence of steam are attributed to a modification of the charge carrier nature. In
spite of low conductivity values (σ ~10−6 S.cm−1 at 881 K), the activation energies are in agreement with that of Y-doped strontium zirconate ceramics (~0.7 eV in air). 相似文献
19.
Thermal conductivity of ozone-safe refrigerant C10M1 in liquid (303.9–342.4 K, 1.23–4.257 MPa) and gaseous (324–398.15 K;
0.672–2.107 MPa) states was studied by the methods of high-frequency thermal waves and coaxial cylinders. The estimated measurement
errors for the temperature, pressure, and thermal conductivity are ±0.02 K, ±1.5 kPa, and ±1.5–2.5 %, correspondingly. Approximation
dependencies for thermal conductivity were obtained over the studied range of temperatures and pressures as well as on the
dew and bubble lines. It is shown that thermal conductivity in the liquid state is additive relative to mass concentrations
of components.
The work was financially supported by the Russian Foundation for Basic Research (grant No. 04-02-16355). 相似文献
20.
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