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1.
A. A. Naberezhnov O. A. Alekseeva P. Yu. Vanina D. Yu. Chernyshov A. A. Sysoeva E. Rysiakiewicz-Pasek 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(3):238-241
Temperature dependences of the order parameter in nanocomposites based on porous borosilicate glasses with mean pore diameters of 20 and 46 nm and filled with sodium nitrite are studied via the diffraction of synchrotron radiation. The mean diffraction sizes of NaNO2 nanoparticles in the pores of these matrices and the temperatures of the transition of sodium nitrite to the ferroelectric state are determined. It is shown that the phase transition for these nanoparticles remains a first-order phase transition. 相似文献
2.
V. S. Gorelik Yu. P. Voinov V. D. Zvorykin I. G. Lebo A. O. Levchenko N. N. Ustinovskii 《Bulletin of the Lebedev Physics Institute》2010,37(3):65-70
We present experimental results on the introduction (laser implantation) of ferroelectric NaNO2 into artificial opal pores upon exposure of a thin powder layer of sodium nitrite applied on the artificial opal surface
to radiation of the ultraviolet excimer laser. Reflection spectra of broadband radiation from the laser-implanted sample surface
are compared with the reflection spectra of pure initial opals, artificial opals impregnated with a saturated aqueous solution
of sodium nitrite and evaporated from solvent, and samples in which NaNO2 was directly introduced in the form of a melt. 相似文献
3.
O. V. Rogazinsksya A. S. Sidorkin S. D. Milovidova A. A. Naberezhnov N. N. Matveev N. G. Popravko A. V. Fokin 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(10):1327-1330
The dielectric nonlinearity and pyroeffect in matrix composite based on porous glass with inclusions of sodium nitrite are
investigated. It is found that the composite polarization turns to zero at a temperature below that of the phase transition
in the bulk NaNO2. The obtained dependence of the pyrocoefficient on temperature also corroborates the existence of the phase transition in
sodium nitrite nanoparticles included in the porous matrix. 相似文献
4.
V. N. Bogomolov D. A. Kurdyukov L. S. Parfen’eva A. V. Prokof’ev S. M. Samoilovich I. A. Smirnov A. Jezowski J. Mucha H. Misiorek 《Physics of the Solid State》1997,39(2):341-346
Data on the thermal conductivity ϰ
ph of the cluster lattice of synthetic opals are analyzed. All opals are divided into two groups according to the temperature
dependence of their ϰ
ph. These are opals-1, whose thermal conductivity behaves like ϰ
ph(T) of quasi-crystalline materials, and opals-2, with a ϰ
ph(T) dependence typical of classical amorphous solids. Possible reasons for this difference are considered. An attempt is made
to explain the complex temperature hysteresis in ϰ
ph(T) observed earlier in opals-2.
Fiz. Tverd. Tela (St. Petersburg) 39, 392–398 (February 1997) 相似文献
5.
S.?V.?Baryshnikov B.?F.?Borisov A.?V.?Gartvik A.?G.?Gorchakov E.?V.?Charnaya W.?B?hlmann D.?Michel 《Acoustical Physics》2009,55(1):55-60
A conventional phase-pulse acoustic method was used to study melting and crystallization of sodium nitrite embedded in the pores of mesoporous silicate matrices. The pore diameter was 20, 37, and 52 Å. The measurements were performed at a frequency of 3–8 MHz in the temperature interval 290–560 K. The temperature dependence of ultrasonic velocity was found to exhibit anomalies corresponding to phase transitions of sodium nitrite. The transitions were smeared in temperature and shifted to lower temperatures from the melting point T b of bulk sodium nitrite; the shift in crystallization temperature was greater than that of the melting temperature. The irreversible character of melting was revealed. The size dependence of the melting temperature of sodium nitrite was obtained. Phenomena observed in the experiments were discussed with the use of different size effect models. 相似文献
6.
V. S. Gorelik Yu. P. Voinov V. D. Zvorykin A. I. Lebo I. G. Lebo A. O. Levchenko N. N. Ustinovsky 《Journal of Russian Laser Research》2010,31(1):79-90
We present the experimental results on implantation of NaNO2 ferroelectric into pores of synthetic opal by illuminating with focused ultraviolet excimer-laser radiation of a sodium nitrite
film located on the synthetic-opal surface. The reflection spectra of broadband radiation from the surface of implanted specimens
are compared with the reflection spectra of initial (without any treatment) opals, synthetic opals filled with a saturated
aqueous solution of sodium nitrite with subsequently evaporated solvent, and specimens with NaNO2 embedded as a melt. The possible mechanisms of shifts of reflected- and transmitted-radiation peaks are analyzed. Methods
of implanting materials with high melting points into pores of 3D photonic crystals are proposed. 相似文献
7.
S. V. Baryshnikov E. V. Stukova E. V. Charnaya C. Tien M. K. Lee W. Böhlmann D. Michel 《Physics of the Solid State》2006,48(3):593-599
NMR and dielectric studies have been performed on NaNO2 loaded in mesoporous matrices of MCM-41 and SBA-15 with pore sizes of 20, 37, and 52 Å. The spin-lattice relaxation rate and 23Na NMR line shape, as well as the complex impedance, were measured within a broad temperature interval including the ferroelectric phase transition in bulk NaNO2. Two different phases of sodium nitrite, the crystalline and melt phases, are shown to coexist under conditions of a restricted geometry. The crystalline phase undergoes a ferroelectric phase transition. The melt fraction increases with temperature. The existence of two phases accounts for all experimental data on NaNO2 under conditions of a restricted geometry. 相似文献
8.
The dynamic and static properties of a supercooled (non-entangled) polymer melt are investigated via molecular-dynamics (MD) simulations. The system is confined between two completely smooth and purely repulsive walls. The
wall-to-wall separation (film thickness), D, is varied from about 3 to about 14 times the bulk radius of gyration. Despite the geometric confinement, the supercooled
films exhibit many qualitative features which were also observed in the bulk and could be analyzed in terms of mode-coupling
theory (MCT). Examples are the two-step relaxation of the incoherent intermediate scattering function, the time-temperature
superposition property of the late time α-process and the space-time factorization of the scattering function on the intermediate
time scale of the MCT β-process. An analysis of the temperature dependence of the α-relaxation time suggests that the critical
temperature, T
c, of MCT decreases with D. If the confinement is not too strong ( D≥10monomer diameter), the static structure factor of the film coincides with that of the bulk when compared for the same distance,
T - T
c(D), to the critical temperature. This suggests that T - T
c(D) is an important temperature scale of our model both in the bulk and in the films.
Received 12 September 2001 相似文献
9.
xSb2O3-40TeO2-(60 − x)
V2O5 glasses with 0 ≤ x ≤ 10 (in mol%) have been
prepared by rapid- melt quenching method. DSC curves of these ternary glasses have been
investigated. The glass transition properties that have been measured and reported in this
paper, include the glass transition
temperature (T
g
), glass transition width
(ΔT
g
), heat capacity
change at glass transition
(ΔC
P
) and
fragility (F). Thermal stability, Poisson’s ratio, fragility and glass
forming tendency of these glasses have been estimated, to determine relationship between
chemical composition and the thermal stability or to interpret the structure of glass. In
addition, Makishima and Makenzie’s theory was applied for determination of Young’s
modulus, bulk modulus and shear modulus, indicating a strong relation between elastic
properties and structure of glass. Generally, results of this work show that glass with
x = 0 has the highest shear, bulk and Young’s moduli which make it as
suitable candidate for the manufacture of strong glass fibers in technological
applications; but it should be mentioned that glass with x = 8 has higher
handling temperature and super resistance against thermal attack. 相似文献
10.
C. Tien E. V. Charnaya S. V. Baryshnikov M. K. Lee S. Y. Sun D. Michel W. Böhlmann 《Physics of the Solid State》2004,46(12):2301-2305
NMR and dielectric studies of NaNO2 loaded into an SBA-15 mesoporous matrix are reported. The spin-lattice relaxation rate and the 23Na NMR line shift, as well as the permittivity, were measured within a broad temperature interval including the ferroelectric phase transition in NaNO2. The phase transition temperature of sodium nitrite in as-prepared samples was shown to differ substantially from that characteristic of a bulk crystal. The permittivity grows strongly in the vicinity of the phase transition. Heating a sample causes the properties of NaNO2 embedded in pores to gradually approach those of bulk crystals. 相似文献
11.
In this work, the melting-point depression and molecular dynamics of hexamethyldisilane confined within five controlled pore
glasses, with mean diameters ranging from 7.9 to 23.9 nm, are studied by high-field (9.4 T) nuclear magnetic resonance (NMR),
and the results are discussed with reference to the bulk substance. The melting-point depression in pores with radiusR follows the simplified Gibbs-Thompson equation ΔT=k
p/(R−s) with ak
p value of 74 K · nm and ans value of 1 nm. To our knowledge, this is the first time thek
p value of hexamethyldisilane is reported. Proton spin-lattice relaxation times (T
1), spin-spin relaxation times (T
2), and diffusivities (D) are reported as a function of temperature. The confinement in the pores gives rise to substantial changes in the molecular
dynamics and the phase behavior. The line-shape measurements reveal a two-phase system assigned to a relatively mobile component
at the pore walls and a crystalline solid at the center of the pores. However, theT
2 measurements show that the mobile phase also embraces a minor component attributed to nonfrozen liquid in pockets or micropores.
The diffusivity of the major narrow-line component is approximately three orders of magnitude larger than that in the plastic
bulk phase, reflecting fast diffusion of mobile molecules. Below the melting region,T
1 of the narrow line is significantly shorter thanT
1 of the broad line, suggesting that the molecular reorientation is more hindered close to the surface than at the center of
the pore. 相似文献
12.
We report measurements of the temperature dependence of the electrical resistivity, ρ(T), and magnetic pen-etration depth, λ(T), for polycrystalline samples of Eu0.5K0.5Fe2As2 with T
c
= 31 K. ρ(T) follows a linear temperature dependence above T
c
and bends over to a weaker temperature dependence around 150 K. The magnetic penetration depth, determined by radio frequency
technique displays an unusual minimum around 4 K which is associated with short-range ordering of localized Eu3+ moments.
The article is published in the original. 相似文献
13.
M. I. Petrov D. A. Balaev K. A. Shaikhutdinov K. S. Aleksandrov 《Physics of the Solid State》1999,41(6):881-886
Measurements of the temperature dependence of the electrical resistance R(T) below the superconducting transition temperature have been performed at different values of the transport current in HTSC+CuO
composites modeling a network of weak S-I-S Josephson junctions (S—superconductor, I—insulator). It has been shown experimentally that the temperature dependence R(T) at different values of the transport current is adequately described by means of the mechanism of thermally activated phase
slippage developed by Ambegaokar and Halperin for tunnel structures. Within the framework of this model we have numerically
calculated the temperature dependence of the critical current J
c(T) as defined by various criteria. Qualitative agreement obtains between the measured and calculated temperature dependences
J
c(T).
Fiz. Tverd. Tela (St. Petersburg) 41, 969–974 (June 1999) 相似文献
14.
The molecular mobility of naphthalene molecules in porous silica has been studied over the temperature range 223?K to 363?K using NMR relaxation times T 2, T 1 and T 1ρ. The investigations were conducted in silicas with nominal pore diameters of 4?nm, 6?nm, 10?nm, 20?nm and 50?nm. The confined solid behaved in a way that indicated it formed a dual phase system consisting of a solid core in the centre of the pores surrounded by a mobile surface layer. The core naphthalene had the same line width as the bulk. The surface layer exhibited a narrower line of a width that suggested the onset of motional narrowing. This behaviour was characteristic of a plastic crystal phase for naphthalene that does not exist in the bulk. The T 1 and T 1ρ results were dominated by surface interactions between the confined naphthalene and the pore wall. Magnetization transfer experiments showed that enhanced relaxation occurred throughout the confined material in a time long compared to T 2 but short compared to T 1 and T 1ρ. Since the line shape ruled out diffusional motion through the rigid lattice naphthalene core, the magnetization transfer must have occurred via spin diffusion. 相似文献
15.
The glass transition in Ge
x
Se1−x
) (0·1 ⩽x ⩽ 0·25) glasses has been investigated using the photoacoustic (PA) technique. It is found that the PA amplitude and phase
undergo anomalous changes at the glass transition temperatureT
g. The amplitude has critical minimum and phase has maximum values atT
g. The variation of the thermal diffusivity, determined by measuring the frequency dependence of the PA amplitude and phase,
with temperature shows sharp decrease near the glass transition temperature. The temperature dependence of the optical energy
gap also has been measured and it shows a decrease with temperature for all compositions, the rate of decrease being higher
for temperatures greater thanT
g. 相似文献
16.
N. Yu. Mikhailin D. V. Shamshur R. V. Parfen’ev V. I. Kozub Yu. M. Gal’perin Yu. A. Kumzerov A. V. Fokin 《Physics of the Solid State》2018,60(6):1068-1072
Superconducting structures Pb–PG formed by filling a porous glass matrix with the lead from melt under pressure have been investigated. Samples with characteristic pore structure diameters of d ≈ 7, 3, and 2 nm have been studied. It has been found that the critical temperature of the superconducting transition in the samples under study is similar to the corresponding value Tc ≈ 7.2 K for bulk lead. At the same time, it has been observed that the critical magnetic field of the nanocomposites, which attains Hc(T = 0 K) ≈ 165 kOe for Pb–PG (3 nm), exceeds several times the value Hc(0) = 803 Oe for bulk lead. The low-temperature magnetic- field dependences of magnetic moment M(H) contain quasi-periodic flux jumps, which vanish with a decrease in the lead nanostructure diameter. A qualitative model of the observed effects is considered. 相似文献
17.
Using the data on dispersion of refractive indices in the visible region, the experimental values of the components L
j
of the Lorentz tensor have been obtained for uniaxial (crystalline, oriented on a substrate, and stretched) films of conjugated
polymers from nanometer to micrometer thicknesses. The dependence of the components L
j
on the axial and planar orientations of macromolecules with respect to the optical axis of the film, technology of fabricating
the films, and chemical structure of macromolecules has been elucidated. The correlation between the components L
j
and the measured parameter η has been determined and the analytical dependence L
j
(η) for films with both types of macromolecular orientation has been established. In the visible region (0 ≤ η ≤ 0.5), the
presence of one point (η = 1/3) of isotropization of the tensor L and three points (η = 0, 1/3, and 0.5) of isotropization of the local field tensor f has been revealed. The point η = 1/3 of isotropization of the tensors L and f has been determined. A comparison has been made between the values of L
j
(η) with predictions of known models of the local field for conjugated polymers. 相似文献
18.
A. I. Yakimov N. P. Stepina A. V. Dvurechenskii L. A. Shcherbakova 《Journal of Experimental and Theoretical Physics》1997,85(3):501-506
The temperature dependence of the hopping conductivity and the relaxation kinetics of the transient current in porous amorphous
silicon are investigated after treatment in a hydrogen plasma at 200 °C. It is discovered that posthydrogenation of the material
increases the dimension of the conducting channel from 2.5 to 3, while suppressing and slowing the relaxation of the transient
current. The results obtained are attributed to passivation of the electrically active dangling bonds on the pore surface
by hydrogen. It is concluded that electron transport in porous amorphous silicon in the temperature range T>T*, where T* lies in the range 130–270 K and depends on the density of states, takes place between superlocalized states of the internal
surface, which is enriched with dangling bonds and acts as a fractal percolation system. When the temperature is lowered below
T*, a transition to one-dimensional hopping conduction in the bulk silicon regions occurs.
Zh. éksp. Teor. Fiz. 112, 926–935 (September 1997) 相似文献
19.
S. N. Bashchenko I. V. Blonskii M. S. Brodyn V. N. Kadan Yu. G. Skryshevskii 《Technical Physics》2001,46(1):63-67
The influence of UV irradiation on temperature dependence of the integral intensity of luminescence I lum(T) in porous silicon was studied. It was found that, if luminescence decays with temperature nonmonotonically, the peak of I lum(T) shifts toward higher temperatures as the exciting radiation density increases. Under UV irradiation, the function I lum(T) becomes monotonically decreasing. If the function I lum(T) is initially monotonically decreasing, UV preirradiation changes the emission spectrum and accelerates temperature quenching of the red-orange emission band. The variation of the amplitude of the pulsed photoacoustic response with UV irradiation dose was studied. The dependence found is explained by the removal of foreign inclusions from the developed surface of porous silicon. An energy level diagram that makes it possible to explain the behavior of I lum(T) is suggested. It is noted that the shape of the function I lum(T) can be used as a test whereby the contributions from dissimilar oscillators to the red-orange emission band are estimated. 相似文献
20.
S. I. Masharov 《Russian Physics Journal》1996,39(9):839-842
A general expression is obtained for the thermodiffusion coefficientD
T of a film, also for its dependence on temperature, film thickness and type of concentration distribution of the interstitials,
according to its profile. In neglecting interaction of interstitials with each other in a model of a film with single-plane
boundaries with the vacuum and the substrate, it is shown thatD
T>D
T
(∞) is possible, whereD
T
(∞) is the thermodiffusion coefficient of a bulk specimen.
Ural State Technical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 43–46, September,
1996. 相似文献