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1.
V. G. Slutskii M. V. Grishin V. A. Kharitonov A. K. Gatin B. R. Shub S. A. Tsyganov 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(3):343-345
Organoboron nanoparticles (C2B10H4) n with weight-average sizes of 8.3, 10.6, and 15.3 nm are synthesized from carborane C2B10H12 by high-temperature pyrolysis of its vapor. The dependence of the weight-average particle size on the temperature and initial carborane vapor pressure of the synthesis is obtained. 相似文献
2.
F. C. Fonseca R. F. Jardim M. T. Escote P. S. Gouveia E. R. Leite E. Longo 《Journal of nanoparticle research》2011,13(2):703-710
In this work, we report on the magnetic properties of nickel nanoparticles (NP) in a SiO2–C thin film matrix, prepared by a polymeric precursor method, with Ni content x in the 0–10 wt% range. Microstructural analyses of the films showed that the Ni NP are homogenously distributed in the SiO2–C matrix and have spherical shape with average diameter of ~10 nm. The magnetic properties reveal features of superparamagnetism
with blocking temperatures T
B ~ 10 K. The average diameter of the Ni NP, estimated from magnetization measurements, was found to be ~4 nm for the x = 3 wt% Ni sample, in excellent agreement with X-ray diffraction data. M versus H hysteresis loops indicated that the Ni
NP are free from a surrounding oxide layer. We have also observed that coercivity (H
C) develops appreciably below T
B, and follows the H
C ∝ [1 – (T/T
B)0.5] relationship, a feature expected for randomly oriented and non-interacting nanoparticles. The extrapolation of H
C to 0 K indicates that coercivity decreases with increasing x, suggesting that dipolar interactions may be relevant in films with x > 3 wt% Ni. 相似文献
3.
The catalytic and the electrocatalytic behavior of MnOx oxides deposited on Yttria Stabilized Zirconia (YSZ) in the form of thin porous films, was studied during the reaction of
methane activation at high methane to oxygen ratios. Experiments were carried out in a continuous flow well-mixed reactor
(CSTR), at atmospheric total pressure and in a temperature range between 500–850 °C. It was found that the electrochemical
pumping of oxygen anions (O2−) through the solid electrolyte (YSZ) affect drastically the rates of CO2, C2H4 and C2H6 formation and consequently the C2 selectivity.
Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997 相似文献
4.
The Jones–Dole B coefficients of the electrolyte Lithium bromide (LiBr), reference salts tetra butyl ammonium tetra phenyl borate (BU4NBPh4), tetra butyl ammonium bromide (BU4NBr), and potassium chloride (KCl) in dimethylsulfoxide (DMSO), water, and DMSO–water mixtures were obtained at different
temperatures range from 25 to 45 °C For this, the relative viscosities were measured for Lithium bromide (LiBr) and reference
salts in DMSO, water, and DMSO–water mixtures at above-mentioned temperatures. The B coefficients of these electrolytes were behaved as structure makers in DMSO, while in H2O and DMSO–H2O mixtures, the B-coefficient values were less positive showing the weak structure-making effect. Ionic viscosity B coefficients allow us to assess the behavior of ions in the solvent mixtures. In this study it was observed that all the
values of ionic B coefficient of (Li+) were positive and small showing the weak structure-making effects. It was also observed that Br− ions maintain negative B coefficient values in all DMSO–H2O mixtures, except in 60% DMSO mole fraction. From this it can be concluded that Br− ion behaved as a structure breaker in water and in all DMSO–H2O mixtures except in 60% DMSO mole fraction mixtures. The low B
± values of alkali metal ions and Br− ions in water are due to the breakdown of the tetrahedral structural of water and the formation of strongly structured solvated
ion. It is also observed that the values of the energy of activation of the flow for LiBr are greater in DMSO–water mixtures
and in pure water than in DMSO. This may be due the presence of a network of hydrogen bonds which cause the hindrance in the
flow of the solution of LiBr in DMSO–water mixtures and in pure water than in DMSO. 相似文献
5.
Xiaohua Jia Huiqing Fan Xiangdong Lou Jiaqiang Xu 《Applied Physics A: Materials Science & Processing》2009,94(4):837-841
The CdSnO3 semiconducting oxide that can be used as a gas-sensitive material for detecting ethanol gas is reported in this paper. CdSnO3 nanoparticles were prepared by a chemical co-precipitation synthesis method, in which the preparation conditions were carefully
controlled. The n-type gas-sensing semiconductors were obtained from the as-synthesized powders calcined at 600°C for 1 h.
The phase and microstructure of the obtained nanoparticles were characterized by X-ray diffraction (XRD), transmission electron
microscopy (TEM), and Brunauer–Emmett–Teller (BET) method with a gas adsorption analyzer. CdSnO3 has a small particle size range of 30–50 nm and a high surface area of 9.12 m2/g, and a uniformity global shape. The gas sensitivity and operating temperature, and selectivity of CdSnO3-based sensors were measured in detail. The gas sensors fabricated by CdSnO3 nanoparticles had good sensitivity and selectivity to vapor of C2H5OH when working temperature at 267°C, the value of gas sensitivity at 100 ppm of C2H5OH gas can reach 11.2 times. Furthermore, gas-sensing mechanism was studied by using chromatographic analysis. 相似文献
6.
Sujittra Daengsakul Charusporn Mongkolkachit Chunpen Thomas Sineenat Siri Ian Thomas Vittaya Amornkitbamrung Santi Maensiri 《Applied Physics A: Materials Science & Processing》2009,96(3):691-699
This study reports the new and simple synthesis of magnetic La0.7Sr0.3MnO3 (LSMO) nanoparticles by thermal decomposition method using acetate salts of La, Sr and Mn as starting materials. To obtain
the LSMO nanoparticles, thermal decomposition of the precursor is carried out at the temperatures of 600, 700, 800, 900, and
1000°C for 6 hours. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM and SEM. Structural characterization
shows that the prepared particles consisted of two phases of LaMnO3 (LMO) and LSMO with crystallite sizes ranging from 18 to 55 nm. All the prepared samples have a perovskite structure which
changes from cubic to rhombohedral with the increase in the thermal decomposition temperature. Basic magnetic characteristics
such as saturation magnetization (M
S) and coercive field (H
C) are evaluated by sample vibrating magnetometry at room temperature (20°C). The samples show soft ferromagnetic behavior
with M
S values of ∼9–55 emu/g and H
C values of ∼8–37 Oe, depending on the crystallite size and thermal decomposition temperature. The relationship between the
crystallite size and the magnetic properties is presented and discussed. The cytotoxicity of synthesized LSMO nanoparticles
was also evaluated with NIH 3T3 cells and the result showed that the synthesized nanoparticles were not toxic to the cells
as determined from cell viability in response to the liquid extraction of LSMO nanoparticles. 相似文献
7.
N. E. Sluchanko A. N. Azarevich A. V. Bogach S. Yu. Gavrilkin V. V. Glushkov S. V. Demishev A. V. Dukhnenko A. B. Lyashchenko K. V. Mitsen V. B. Filipov 《JETP Letters》2011,94(8):642-646
The specific heat of the ZrB12 compound in the normal and superconducting states (T
C
≈ 6 K) has been studied in the 1.9–7 K temperature range for high-quality single crystals with different relative contents
of boron isotopes. For Zr10B12, ZrnatB12, and Zr11B12 dodecaborides, the electron density of states and the electronphonon coupling constant, λe-ph ∼ 0.4, are found. The dependence of the thermodynamic and upper critical fields, as well as of the Ginzburg-Landau parameter
(κ = 0.8–1.14) on temperature and isotope composition is determined. The results suggest the existence of the magnetic field
induced phase transition at T* = 4–5 K, which is not related to the transition from type-I to type-II superconductivity. The possibilities of the existence
of two-gap superconductivity and a structural phase transition at T* in zirconium dodecaboride are discussed. 相似文献
8.
Manganese-doped ZnSiAs<Subscript>2</Subscript> chalcopyrite: A new advanced material for spintronics
L.?I.?Koroleva D.?M.?Zashchirinski? T.?M.?Khapaeva S.?F.?Marenkin I.?V.?Fedorchenko R.?Szymczak B.?Krzumanska V.?Dobrovol’ski? L.?Kilanski? 《Physics of the Solid State》2009,51(2):303-308
A new spintronics material with the Curie temperature above room temperature, the ZnSiAs2 chalcopyrite doped with 1 and 2 wt % Mn, is synthesized. The magnetization, electrical resistivity, magnetoresistance, and
the Hall effect of these compositions are studied. The temperature dependence of the electrical resistivity follows a semiconducting
pattern with an activation energy of 0.12–0.38 eV (in the temperature range 124 K ≤ T ≤ 263 K for both compositions). The hole mobility and concentration are 1.33, 2.13 cm2/V s and 2.2 × 1016, 8 × 1016 cm−3 at T = 293 K for the 1 and 2 wt % Mn compositions, respectively. The magnetoresistance of both compositions, including the region
of the Curie point, does not exceed 0.4%. The temperature dependence of the magnetization M(T) of both compositions exhibits a complicated character; indeed, for T ≤ 15 K, it is characteristic of superparamagnets, while for T > 15 K, spontaneous magnetization appears which correspond to a decreased magnetic moment per formula unit as compared to
that which would be observed upon complete ferromagnetic ordering of Mn2+ spins or antiferromagnetic ordering of spins of the Mn2+ and Mn3+ ions. Thus, for T > 15 K, it is a frustrated ferro- or ferrimagnet. It is found that, unlike the conventional superparamagnets, the cluster
moment μ
c
in these compositions depends on the magnetic field: ∼12000–20000μB for H = 0.1 kOe, ∼52–55μB for H = 11 kOe, and ∼8.6–11.0μB at H = 50 kOe for the compositions with 1 and 2 wt % Mn, respectively. The specific features of the magnetic properties are explained
by the competition between the carrier-mediated exchange and superexchange interactions. 相似文献
9.
A. E. Gorodetskii V. L. Bukhovets R. Kh. Zalavutdinov A. P. Zakharov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(6):928-934
Transport of exhausted thermonuclear fuel in the ITER divertor and pumping duct was modeled on a specially designed dc glow
discharge setup using mass spectrometry, optical and electron microscopy, and electron probe microanalysis. Transport and
deposition of hydrocarbon radicals transferred in an H2/C
x
H
yx
mixture through a hollow stainless steel anode at a total mixture pressure of 8–212 Pa and a methane content to 15 mol %
were considered. It was shown that deposition of radicals and ions (CH3, C2H3, C2H5) with kinetic energies of 0.03–3 eV on the anode inner surface at 600 K was suppressed to a large extent. In the temperature
range of 600–800 K, deposition of ions and radicals with kinetic energy of ~3 eV was partially restored with the formation
of soft a-C:H films, while thermalized radicals were not condensed. 相似文献
10.
E. E. Shalygina N. V. Umnova P. P. Umnov V. V. Molokanov V. V. Samsonova A. N. Shalygin A. A. Rozhnovskaya 《Physics of the Solid State》2012,54(2):287-292
The magnetic properties of initial and heat-treated Co69Fe4Cr4Si12B11 microwires in a glass shell with the diameter D = 125 μm and the diameter of the amorphous metallic core d = 90 μm produced by the Ulitovsky-Taylor method have been studied. It has been found that the magnetic characteristics, in
particular, the saturation field H
S
and the coercive force H
C
of the samples annealed at a temperature T < 300°C do not differ from H
S
and H
C
of the initial microwire, and those of the samples annealed at T ≥ 400°C increase by almost one order of magnitude. The obtained experimental data have been explained by the structural features
of the microwires. The near-surface values of H
S
and H
C
at T < 300°C are found to be larger than the bulk values by a factor of 5–10. These experimental data have been explained by the
existence of structural and chemical ingomogeneities in the near-surface layer, which are inherent in amorphous materials.
This difference decreases with a further increase in the annealing temperature, but H
S
and H
C
increase substantially. This fact has been explained by the beginning of the microwire crystallization. 相似文献
11.
Magnetic properties, arising from surface exchange and interparticle interactions of the Fe3O4 (magnetite) nanoparticles, were investigated in the temperature range of 5–300 and 120–300 K using vibrating sample magnetometer
technique and electron spin resonance spectroscopy, respectively. The research was based on to figure out the origin of intraparticle
interactions and the change of interparticle interactions in wide size range Fe3O4 nanoparticles. The analyses were done for samples having almost same particle size distributions. The average particle sizes
were changed in between 30 ± 2 and 34 ± 2 nm. The observed magnetization values were demonstrated the mixture of single-domain
size particles, exhibiting both single-domain (SD) and superparamagnetic (SPM) states. The symmetry of resonance curves changed
according to the ratio of SD and SPM-stated particles in mixture under located temperature. The changes of anisotropy up to
domain state were understood by freezing magnetic moment in glycerol matrix from room temperature to 120 K under 5-kG field.
The shift of H
R values to higher magnetic fields and the more symmetric resonance spectrum proved the effect of anisotropy and interparticle
interactions fields on magnetic behave. In addition, the origin of intra-interaction was exposed from Fe3+ centers and exchange coupling in between Fe2+, Fe3+, and O−, and Fe3+ centers found from g factor (g). 相似文献
12.
T. S. Zhuravleva O. P. Ivanova E. P. Krinichnaya I. A. Misurkin S. V. Titov S. A. Zav’yalov E. I. Grigor’ev 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(4):681-688
For poly-p-xylylene + CdS (PPX + CdS) nanocomposite films, the dependences of the photo-conductivity σ
ph
(T) on the concentration C of CdS nanoparticles, intensity and wavelength of exciting light, and temperature T within 15–300 K are examined. An appreciable photocurrent appears at C ≥ 10 vol %, when a large percolation cluster of CdS nanoparticles is formed. The photocurrent spectrum is compared to the
absorption spectrum of the film. The photocurrent I
ph
(P) increases with the intensity of light flux P in a wavelength range near 435 nm according to the I
ph
(P) ∼ P
n
power law, where n < 1. At 15 K, the photoconductivity of films with C ≈ 11.5 and 13.5 vol % is higher than that of a pure CdS film (C = 100 vol %) by factors of ≈100 and ≈30, respectively. For films with C > 11.5 vol %, the σ
ph
(T) dependence at low T exhibits a metal-like character (σ
ph
(T) decreases with increasing temperature). Atomic force microscopy is used to examine the surface topography of PPX + CdS films,
which is found to be strongly dependent on the concentration of nanoparticles. The dark conductivity and photoconductivity
of nanocomposite films arise due to the thermo- and photoexcitation transfer of electrons from the CdS nanoparticles to the
PPX matrix with the formation of an electronic double layer at the PPX matrix-large percolation CdS cluster interface, a process
that populates the phenyl rings of the adjacent PPX layer with excess electrons. As a result, various mechanisms of electron
transfer in the polymer matrix can be realized: Mott’s hopping conduction mechanism with variable-range hopping in the matrix
between CdS clusters and the metal-like behavior of the conductivity in the polymer shell of the large cluster at low temperatures.
The polymer shell contains excess electrons on the phenyl rings -C6H4- in the composition of anion-resonances -C6H4−-. 相似文献
13.
D. A. Rudakov V. I. Potkin A. N. Ryabtsev I. B. Sivaev 《Journal of Applied Spectroscopy》2006,73(4):616-619
In the 11B NMR spectra of dihalo derivatives of bis(dicarbollyl)cobalt(III), we have identified a correlation between the 11B NMR chemical shifts of substituted boron atoms and boron atoms found in other positions on the carborane skeleton. We have
observed an increased shielding effect for fluorine atoms (compared with other halogens), manifested in an upfield shift of
the 11B NMR signals for antipodal and trans boron atoms. For the fluorine-containing compound Bu4N+ [8,8′-F2-3,3′-Co(1,2-C2B9H10)2]−, we propose the following sequence of electron density transfer: B(8) → {B(6) and B(10)} → B(4, 7).
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 547–549 (cont.), July–August, 2006. 相似文献
14.
The [N(CH3)4][N(C2H5)4]ZnCl4 compound has been synthesized by a solution-based chemical method. The X-ray diffraction study at room temperature revealed
an orthorhombic system with P21212 space group. The complex impedance has been investigated in the temperature and frequency ranges 420–520 K and 200 Hz–5 MHz,
respectively. The grain interior and grain boundary contribution to the electrical response in the material have been identified.
Dielectric data were analyzed using the complex electrical modulus M
* for the sample at various temperature. The modulus plots can be characterized by full width at half height or in terms of
a non-exponential decay function ϕ(t) = exp[(−t/τ)
β
]. The detailed conductivity study indicated that the electrical conduction in the material is a thermally activated process.
The variation of the AC conductivity with frequency at different temperatures obeys the Almond and West universal law. 相似文献
15.
Cheng-Yen Tsai Hsing-Cheng Hsi Hsunling Bai Kuo-Shuh Fan Chienchih Chen 《Journal of nanoparticle research》2011,13(10):4739-4748
Oxygen-vacant titanium dioxide (TiO2−x
) nanoparticles were synthesized using thermal plasma as a heating source at various applied plasma currents and He/Ar ratios.
Samples with diverse characteristics were developed and the mercury removal effectiveness was subsequently evaluated. TiO2 nanoparticles possessing high purity and uniform particle sizes were successfully synthesized using metal titanium and O2 as precursors and Ar as plasma gas. TiO2−x
in anatase phase with a particle size at 5–10 nm was formed at the He/Ar volume ratio of 25/75. Further increasing the He/Ar
ratio elevated the plasma temperature, causing the tungsten to melt, vaporize from the cathode, and then dope into the formed
TiO2 nanoparticles. The doped W appeared to inhibit the growth of nanoparticles and decrease the crystallinity of formed anatase.
The effectiveness of oxygen-vacant sites on Hg0 removal under the visible light circumstance was confirmed. Hg0 removal by the TiO2−x
nanoparticles was enhanced by increasing the O2 concentration. However, moisture reduced Hg0 capture, especially when light irradiation was applied. The reduction in Hg0 capture may be resulted from the competitive adsorption of H2O on the active sites of TiO2−x
with Hg0 and transformed Hg2+. 相似文献
16.
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
17.
A sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) was evaluated for the detection of trace levels of ethylene
at atmospheric pressure using a fiber coupled DFB diode laser emitting in the 1.62 μm spectral range. A noise-equivalent QEPAS signal of ∼4 ppm C2H4 was achieved for a 0.7 s data acquisition time using wavelength-modulation with a second-harmonic detection scheme on the
strongest C2H4 absorption peak at 6177.14 cm−1 with an average optical power of ∼15 mW. Improved detection sensitivity of 0.5 and 0.3 ppm C2H4 (1σ) was demonstrated using longer averaging time of 70 and 700 s, respectively. Important characteristics for the QEPAS based
sensor operation in real-world conditions are presented, particularly the influence of external temperature variations. Furthermore,
the response time of the ethylene sensor was measured in different configurations and it is shown that the QEPAS technique
can provide a response time in a few seconds range even without active gas flow. 相似文献
18.
V. N. Bagratashvili S. G. Dorofeev A. A. Ischenko V. V. Koltashev N. N. Kononov A. A. Krutikova A. O. Rybaltovskii G. V. Fetisov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(7):1164-1170
With the use of supercritical carbon dioxide (SC-CO2), the matrix immobilization of photoluminescent silicon nanocrystals (nc-Si) in polytetrafluoroethylene microparticles (mp-PTFE)
is performed, which leads to the formation of mp-PTFE/nc-Si photoluminescent nanocomposite containing ∼103–104 nc-Si particles per mp-PTFE particle (1–2 μm in size). This approach is based on the effect of polymer swelling in SC-CO2, efficient SC-CO2-assisted transport of nanoparticles into the internal free volume of the polymer, and contraction of the nanocomposite after
the release of CO2, an effect that prevents the subsequent agglutination of nanoparticles. Particles of nc-Si photoluminescent in the visible
spectrum were synthesized from silicon suboxide powder (SiO
x
, x ≈ 1) heated at various temperatures within 25–950°C and then etched in concentrated hydrofluoric acid. The hydrosilylation
procedure was used to graft 1-octadecene molecules to the surface of nc-Si particles. As a result, the photoluminescence intensity
of nc-Si increased substantially. According to TEM images and small angle X-ray scattering data, the maximum size of nc-Si
particles did not exceed 5 nm and 7 nm, respectively, and the core of these nanoparticles consisted of crystalline silicon.
The structure and spectral properties of the initial nc-Si particles and synthesized mp-PTFE/nc-Si photoluminescent nanocomposite
microparticles were studied. 相似文献
19.
Monodisperse α-Fe2O3 microspheres have been selectively synthesized through a facile hydrothermal method without the assistance of any surfactant,
employing FeCl3·6H2O and NH4NaHPO4 as initial materials. The products were characterized by X-ray diffraction, scanning electron microscopy, and transmission
electron microscopy. α-Fe2O3 microspheres with average size about 250 nm were constructed by single crystalline nanoparticles with average diameter about
15 nm. The investigation on the evolution formation revealed that growth temperature was critical to control the assembly
of the fresh formed nanocrystallites, and the microsphere formation was proved to be the Ostwald ripening process by tracking
the structures of the products at different growth temperature. α-Fe2O3 microspheres showed a weak ferromagnetic behavior with a remanent magnetization of 0.208 emu g−1 and a coercivity of 1,034.27 Oe at room temperature. 相似文献
20.
M. V. Grishin A. K. Gatin V. G. Slutskii V. A. Kharitonov B. R. Shub 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(4):383-388
Scanning tunneling microscopy and spectroscopy are used to determine the shape and electronic structure of organoboron nanoparticles formed during high-temperature pyrolysis of C2B10H12 carborane vapor. Spherical, lenticular, and shapeless nanoparticles are found. Spherical and lenticular particles exhibit metallic conduction, whereas shapeless particles show semiconductor properties. 相似文献