共查询到20条相似文献,搜索用时 0 毫秒
1.
Juan C. del Valle Enrique Camarillo Julio A. Gonzalo Carmen Aragó Manuel Marqués 《哲学杂志》2015,95(7):683-690
Recently, the paraelectric response of water was investigated in the range 0–100 °C. It showed an almost perfect Curie–Weiss behaviour up to 60 °C, but a slight change in slope of 1/εd versus T at 60 °C was overlooked. In this work, we report optical extinction measurements on metallic (gold and silver) nanoparticles dispersed in water, annealed at various temperatures in the range from 20 to 90 °C. An anomalous response at 60 °C is clearly detectable, which we associate to a subtle structural transformation in the water molecules at that temperature. This water anomaly is also manifested by means of a blue shift in the longitudinal surface plasmon resonance of the metallic nanoparticles for the solutions annealed at temperatures higher than about 60 °C. A reanalysis of 1/εd (T) for water in the whole temperature range leads us to conclude that the water molecule undergoes a subtle transformation from a low temperature (0–60 °C) configuration with a dipole moment μ1 = 2.18 D (close to the molecular dipole moment of ice) to a high temperature (60–100 °C) configuration with μ2 = 1.87 D (identical to the molecular dipole moment in water vapour). 相似文献
2.
The aim of this work is to reveal the results of the reaction of nepheline mineral with concentrated sulfuric acid. The valence states of iron atoms are determined in the nepheline and the reacted nepheline. The existence of iron containing magnetic particles in the sediment is shown. The differences in the lineshape are discussed also and are associated with a transfer from one phase to another of the magnetic particles. 相似文献
3.
N. N. Sibeldin 《Journal of Experimental and Theoretical Physics》2016,122(3):587-601
A brief review is given of the studies in which quasi-two-dimensional spatially-direct and dipolar electron–hole liquids in Si/SiGe/Si type-II heterostructures with a low Ge content in the SiGe layer were discovered and investigated. 相似文献
4.
Morishita T 《Physical review letters》2006,97(16):165502
We present an extensive set of isothermal-isobaric first-principles molecular-dynamics simulations of liquid silicon over a temperature range of 950-1700 K. We find that the tetrahedral order gradually grows upon cooling to approximately 1200 K, but that the growth accelerates significantly below approximately 1200 K. This growth process gives rise to anomalous changes in density and liquid structure upon supercooling. In particular, we find that the atomic coordination number remains constant to approximately 1200 K and then begins to decrease below approximately 1200 K, which resolves the existing controversy regarding liquid structure in the supercooled regime [T. H. Kim, Phys. Rev. Lett. 95, 085501 (2005)10.1103/PhysRevLett.95.085501]. 相似文献
5.
《声学学报:英文版》1991,(3)
The directionality of the sound generated by laser-induced liq-uid breakdown in water is investigated both theoretically and experimen-tally.The theoretical analysis is based on the following model.A seriesof small spherical cavities including plasma are homogeneously distributedon a short straight line segment and every such cavity may be consideredas a point source radiating acoustic impulse.Theoretical expressions ofthe relations between the amplitude and width of acoustic impulse and thereceiving direction are given.Experimental results are in agreement withtheoretical predictions. 相似文献
6.
V. ?vr?ek T. Sasaki R. Katoh Y. Shimizu N. Koshizaki 《Applied physics. B, Lasers and optics》2009,94(1):133-139
Blue luminescent colloidal silicon nanocrystals (Si-ncs) were synthesized at room temperature by nanosecond pulsed laser ablation
of a single-crystal silicon target in de-ionized water. Irregular Si-nc fragments obtained by laser ablation are stabilized
into regularly shaped, spherical, and well-separated aggregates during the aging process in water. Aging in de-ionized water
for several weeks improved the photoluminescence (PL) intensity. At least two weeks of aging are necessary for observation
of broad blue room temperature PL with a maximum centered at 420 nm. Detailed structural analysis revealed that agglomerates
after aging for several months contain Si-ncs with irregular shape smaller than the quantum confinement limit (<5 nm). These
blue luminescent Si-ncs dispersed in de-ionized water exhibited a PL decay time of 6 ns, which is much faster than that of
Si-ncs prepared in traditional ways (usually on the order of microseconds). The oxidized Si-ncs with quantum confinement effects
are responsible for a PL band around 400 nm visible to the naked eye at room temperature. 相似文献
7.
This paper presents a front-tracking method for studying the large deformation of a liquid capsule enclosed by a thin shell in a shear flow. The interaction between the fluid and the shell body is accomplished through an implicit immersed boundary method. An improved thin-shell model for computing the forces acting on the shell middle surface during the deformation is described in surface curvilinear coordinates and within the framework of the principle of virtual displacements. This thin-shell model takes full account of in-plane tensions and bending moments developing due to the shell thickness and a preferred three-dimensional membrane structure. The approximation of the shell middle surface is performed through the use of the Catmull–Clark subdivision surfaces. The resulting limit surface is C2-continuous everywhere except at a small number of extraordinary nodes where it retains C1 continuity. The smoothness of the limit surface significantly improves the ability of our method in simulating capsules enclosed by hyperelastic thin shells with different shapes and physical properties. The present numerical technique has been validated by several examples including an inflation of a spherical shell and deformations of spherical, ellipsoidal and biconcave capsules in the shear flow. In addition, different types of motion such as tank-treading, swinging, tumbling and transition from tumbling to swinging have been studied over a range of shear rates, viscosity ratios and bending modulus. 相似文献
8.
Zasetsky AY 《Physical review letters》2011,107(11):117601
Dielectric relaxation in liquid water is studied using molecular dynamics (MD) simulations in the temperature range of 240 to 340?K at atmospheric pressure. The main dielectric and fast relaxation mode are identified in the spectra of dipole moment autocorrelation functions. The microscopic origin of the fast dielectric relaxation process, which takes place on a time scale of subpicoseconds at room temperature, is discussed. A new hypothesis for the fast dielectric mode is presented. It is based on the assumption of the intrawell rotational relaxation taking place during the waiting period between thermally activated large angle jumps occurring in the course of changing H-bond partners. 相似文献
9.
V. E. Borisenko P. I. Gaiduk V. V. Gribkovskii F. F. Komarov V. S. Solov'yev 《辐射效应与固体损伤》2013,168(3):109-115
Abstract The silicon layers structure after As+?ion implantation and subsequent pulse annealings, which were carried out in nanosecond (Q-switched ruby laser) or/and few seconds (halogen lamps) time intervals, has been studied by transmission electron microscopy techniques. It has been shawn that the structure state is determined to a large extend by pulse annealing parameters. In the case of second pulse annealing the level of ion-implanted layer disordering affects considerably the obtained structure. 相似文献
10.
《Composite Interfaces》2013,20(7-9):771-779
Interaction on the solid–liquid surface in dispersions of microcrystalline cellulose (MCC) with various particle sizes has been studied by means of rheological methods. It was shown that the MCC dispersions possess shear-thinning rheological properties. An inversely proportional relationship between the average particle size of the MCC particles and the viscosity of the dispersions was discovered. This phenomenon is explained by the decrease of water mobility with increase in the specific surface of the MCC particles. Irreversible closing of the MCC pores reduces the viscosity of water dispersions. Addition of some water-soluble polymers leads to a considerable increase in viscosity due to formation of macromolecular net composed of solid particles. 相似文献
11.
Thermal conductivity and thermal diffusivity coefficients of liquid indium have been determined in the range of temperatures
from 470 to 1275 K by the laser flash method. Errors of heat transfer coefficients are ±(3.5–5) %. Approximating equations
and tables of reference data have been developed for temperature dependence of properties. Measurement results have been compared
with the data available in the literature. Temperature dependence of Lorentz number has been calculated up to 1000 K. 相似文献
12.
《Journal of Quantitative Spectroscopy & Radiative Transfer》1964,4(3):441-451
The spectral absorption coefficients of liquid water have been measured between 2200 and 3000 cm-1 and between 3700 and 7600 cm-1 at temperatures of 27, 89, 159, and 209°C. The integrated intensities for the entire spectral regions extending from 4600 to 5900 cm-1 and from 5900 to 7600 cm-1 have also been determined at each of the specified temperatures. Following Buijs and Choppin, the experimental data have been used, in a highly simplified analysis, for the determination of hydrogen bonding in liquid water on the assumption that water consists of clusters containing only zero, one or two hydrogen bonds per molecule. We have also indicated briefly a more complete analysis of the experimental measurements in which the full range of results on spectral absorption coefficients as a continuous function of frequency is properly utilized. 相似文献
13.
Cubic-stabilized ((DyO1.5) x –(WO3) y –(BiO1.5)1 − x − y ) electrolytes (DWSB) with much higher conductivity than (ErO1.5)0.2(BiO1.5)0.8, 20ESB, were developed through a double-doping strategy. (DyO1.5)0.08–(WO3)0.04–(BiO1.5)0.88, 8D4WSB, is the highest conductivity composition but underwent the greatest conductivity degradation at 500 °C due to its low total dopant concentration. The effect of dopant composition on conductivity behavior with time at 500 °C demonstrates that there is a trade-off between initial conductivity and long-term stability at this temperature. Therefore, it is necessary to find an optimal total and relative concentration of dopants to provide the enhanced long-term stability needed to make this DWSB electrolyte system feasible for 500 °C operation. To this end, it was found that (DyO1.5)0.25–(WO3)0.05–(BiO1.5)0.70, 25D5WSB, maintained a conductivity of 0.0068 S/cm without appreciable degradation after annealing at 500 °C for 500 h. Moreover, since bismuth oxide-based electrolytes do not exhibit any grain boundary impedance, the total conductivity of 25D5WSB is significantly higher than that of alternate electrolytes (e.g., GDC: Gd0.1Ce0.9O1.95) at this temperature. 相似文献
14.
16.
110 °C thermoluminescence (TL) peak in quartz is well known due to its pre-dose effect, which is used in dating technique. The generally accepted mechanism for the production of this peak is based on Ge impurity contained in quartz. Its role is to substitute for Si in SiO4 tetrahedron and under irradiation gives rise to [GeO4/e?]? electron centre. Heating for TL read out liberates electron that recombines with hole in [AlO4/h]° or [H3O4/h]° centres emitting photon. The investigation, carried out on blue quartz, green quartz, black quartz, pink quartz, red quartz, sulphurous quartz, milky quartz, alpha quartz and synthetic quartz, has shown that the 110 °C TL peak in all these varieties of quartz has no correlation with the respective Ge content. Electron paramagnetic resonance (EPR) measurements on any of these varieties of quartz revealed a signal with g1=2.0004, g2=1.9986 and g3=1.974 and this signal does not appear to correspond to any known EPR signals in alpha quartz. Furthermore, isothermal decay measurements are carried out on the above mentioned EPR signal and 110 °C TL peak in alpha, blue and green quartz. A close correlation has been observed in the decay behavior. A new mechanism is proposed based on an interstitial O? centre. 相似文献
17.
18.
Gediminas Galinis Gauthier Torricelli Atea Akraiam Klaus von Haeften 《Journal of nanoparticle research》2012,14(8):1-6
Experimental studies have been performed on unisize tungsten clusters constructed on a graphite surface by means of the scanning tunneling microscopy. It was found that the geometry of the clusters changes instantaneously from a monatomic-layer tungsten disk to a diatomic-layer structure between the cluster size of 10 and 11. We concluded that this transition is driven by a change in the dominant interaction from the attractive electrostatic interaction between the cluster and the surface to intracluster cohesive metallic interaction. 相似文献
19.
We studied the dielectric properties of nano-sized liquid water samples confined in polymerized silicates MCM-41 characterized
by pore sizes 3–10 nm. Freezing temperature suppression in nanopores helps keep the water samples in liquid form at temperatures
well below 0°C and thus effectively study the properties of supercooled liquid water. We report the first direct measurements
of the dielectric constant by the dielectric spectroscopy method and demonstrate very clear signatures of the second-order
phase transition of ferroelectric nature at temperatures next to the λ-point in the supercooled bulk water in full agreement
with the recently developed model of the polar liquid. 相似文献
20.
X. Y. Chen J. Lin J. M. Liu Z. G. Liu 《Applied Physics A: Materials Science & Processing》2009,94(3):649-656
It was found that laser irradiation of silicon immersed in water can lead to regular hexagonal patterns on the silicon surface
with period of ∼10 μm within several tens of minutes. The formation and the evolution of the surface patterns can be interpreted
as Rayleigh–Taylor instability of the melted silicon layer under the interfacial pressure formed by fast boiling of the interfacial
water at the laser-heated silicon surface. Based on the mechanism, a liquid film equation was proposed. The time evolution
of the patterns was then compared with that of the well-defined classical Rayleigh–Taylor instability system. It showed that
the two systems were qualitatively consistent in several aspects, supporting the Rayleigh–Taylor instability mechanism proposed. 相似文献