Dielectric response of water confined in metal–organic frameworks

Dielectric response of water confined in metal–organic frameworks was investigated in broad temperature range from 140 to 410 K and from 20 Hz to 1 MHz using a capacitance bridge. Several dispersion regions of characteristic shape were found, caused by freezing–melting of adsorbed water molecules, which disappear after a prolonged heating at 410 K. Temperature dependencies of relaxation time of confined water molecules were obtained and are compared to those of water confined in MCM-41 mesoporous molecular sieves.     

Enhanced long-term stability of bismuth oxide-based electrolytes for operation at 500 °C

Cubic-stabilized ((DyO_1.5) _x –(WO₃) _y –(BiO_1.5)_{1 − x − y} ) electrolytes (DWSB) with much higher conductivity than (ErO_1.5)_0.2(BiO_1.5)_0.8, 20ESB, were developed through a double-doping strategy. (DyO_1.5)_0.08–(WO₃)_0.04–(BiO_1.5)_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 (DyO_1.5)_0.25–(WO₃)_0.05–(BiO_1.5)_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: Gd_0.1Ce_0.9O_1.95) at this temperature.     

Origin of the anomalous long lifetime of ¹⁴C

We report the microscopic origins of the anomalously suppressed beta decay of 1?C to 1?N using the ab initio no-core shell model with the Hamiltonian from the chiral effective field theory including three-nucleon force terms. The three-nucleon force induces unexpectedly large cancellations within the p shell between contributions to beta decay, which reduce the traditionally large contributions from the nucleon-nucleon interactions by an order of magnitude, leading to the long lifetime of 1?C.     

Predictability of the appearance of anomalous waves at sufficiently small Benjamin–Feir indices

The numerical simulation of the nonlinear dynamics of random sea waves at sufficiently small Benjamin–Feir indices and its comparison with the linear dynamics (at the coincidence of spatial Fourier harmonics near a spectral peak at a certain time t_p) indicate that the appearance of a rogue wave can be predicted in advance. If the linear approximation shows the presence of a sufficiently extensive and/or high group of waves in the near future after t_p, an anomalous wave is almost necessarily formed in the nonlinear model. The interval of reliable forecasting covers several hundred wave periods, which can be quite sufficient in practice for, e.g., avoiding the meeting of a ship with a giant wave.     

Interaction of binary cuprates with oxygen and water vapor at temperatures of 200–400°C

Interaction of binary cuprates with oxygen and water vapor at T = 200–400°C has been studied. It has been established that only compounds containing oxygen vacancy chains in their structure can absorb oxygen and moisture from annealing atmosphere. Absorption of oxygen brings about decrease in the lattice parameters while embedding of OH^? groups leads to their growth. In contrast to YBa₂Cu₃O _y , binary cuprates do not undergo phase transitions in interaction with the atmosphere. Saturation with water and formation of oxyhydroxides is followed by their hydrolytic decomposition involving formation of simpler oxides and hydroxides.     

Dielectric properties of potassium–sodium niobate ceramics at low frequencies

ABSTRACT

A study of the effects of ageing history on the electrical properties of lead-free ferroelectric ceramics of (K_0.5Na_0.5)(Nb_1?xSb_x)O₃ + 0.5 mol% MnO₂ and (K_0.5Na_0.5)(Nb_1?xTa_x)O₃ + 0.5 mol%MnO₂ for x = 0.05 is reported. The samples after storage at a constant temperature have been subject to infra-low-frequency electric field and radiation. Differences of the photoelectric response between the two examined compounds were found and the restoration of polarisation in the aged ceramic materials by cycles of applied field is discussed.     

Characterization of a Dielectric Barrier Plasma Gun Discharging at Atmospheric Pressure

We develop a plasma gun based on dielectric barrier discharge and working at atmospheric pressure. A theoretical model to predict the gun discharge voltage is built, whirh is in agreement with the experimental results. After inwstigating the characterization of discharging gun and utilizing it for polymerization, we find that the gun can be used as a source to generate a stable uniform plasma for different plasma-processing technologies.     

Effect of exposure to air on sheet resistance and phase composition of Co silicides annealed at a low temperature of 470 °C

Attention has been attracted to Co silicides due to their superior properties in deep-submicron integrated circuit technology. In this paper, the effect of exposure to air on the properties of Co silicides has been studied. Co films of 20-nm thickness were deposited onto polysilicon layers using Ar sputtering. After deposition, the samples were exposed to air at room temperature for different times, ranging from 0 to 48 h, before a rapid thermal annealing (RTA) at 470 °C. It is found that exposure to air significantly changes the sheet resistance (R_s) and the phase composition of the silicides. The sample exposed to air for 48 h has R_sof∼71 Ω/sq, which is about 10% lower than that for the sample annealed immediately. This is due to the fact that more Co₂Si phase and less CoSi phase are formed in the former sample. The mechanism can be attributed to the gases in air (e.g. O₂), which contaminate the Co/Si interface and act as a kinetic barrier during the subsequent RTA. It has been demonstrated that gaseous contamination from air strongly influences the CoSi_x phase transformation. Received: 3 June 2002 / Accepted: 29 June 2002 / Published online: 28 October 2002 RID="*" ID="*"Corresponding author. E-mail: qiang.huang@philips.com     

On the role of a weak hydrogen bond OH…O in the formation of the anomalous dielectric response of crystals and polymers near 40°C

In some crystals, polymers, and gels that contain hydrogen bonds OH…O, NH…O of length 2.8–3 Å or water molecules, gigantic anomaly of dielectric permittivity (? ～ 10³–10⁶) is observed in certain circumstances at frequencies of 1–10⁶ Hz, which is accompanied by peculiarities in conductivity σ and dielectric losses tanδ. In crystals this effect appears after a sudden cooling to ?50°C and it is observed at slow heating in the range of 20–40°C. At the return temperature course from 40°C dependences ?(T), σ(T), and tanδ(T) have their usual values. Anomalies in objects that differ by their compositions are unified by their temperatures, which are all close to 40°C. Authors have made an attempt to explain the similarity of these phenomena by the features of hydrogen bonds that are present in the objects.     

Dielectric Properties of Nuclear Matter with the ωNN Interaction at High Temperature

Based on the QHD-1 field equation, the dielectric constant of nuclear matter with the ωNN interaction has been obtained in the framework of kinetic theory. Furthermore, the characters and physical background of the dielectric constant at high temperature is analyzed in detail.     

Effect of temperature on the morphology of nanobubbles at mica/water interface

The great implication of nanobubbles at a solid/water interface has drawn wide attention of the scientific community and industries. However, the fundamental properties of nanobubbles remain unknown as yet. In this paper, the temperature effects on the morphology of nanobubbles at the mica/water interface are explored through the combination of AFM direct image with the temperature control. The results demonstrate that the apparent height of nanobubbles in AFM images is kept almost constant with the increase of temperature, whilst the lateral size of nanobubbles changes significantly. As the temperature increases from 28℃ to 42℃, the lateral size of nanobubbles increases, reaching a maximum at about 37℃, and then decreases at a higher temperature. The possible explanation for the size change of nanobubbles with temperature is suggested.     

Anomalies of the natural convection of water near 3.98°C

Natural convection of water in a cylindrical cavity with an open surface at a temperature of about 3.98°C (temperature of the maximum water density) is accompanied by typical anomalies on time dependences of temperatures of water layers. In particular, stabilization of temperature T_st is observed in the bottom region of the cavity and duration of such stabilization t_st may reach several hours depending on the experimental conditions. The results for solutions of sodium chloride and ethanol at a relatively low rate of water cooling show that temperature T_st coincides with temperature T_max corresponding to the maximum density of solutions.     

Anomalies of the electrical conductance of water near 4°C

The dependences of the electrical conductance of water (G) on temperature T upon quasi-static heating from 0 to 7°C with a rate of 0.1°C per 200?C250 s have been obtained by the capacitance method in the sound frequency ranges. Anomalies have been found in the dependences G(T) near 4°C for water containing charge carriers of different types and concentrations.     

Laser-accelerated self-assembly of colloidal particles at the water–air interface

We experimentally demonstrate that optical tweezers can be used to accelerate the self-assembly of colloidal particles at a water–air interface in this Letter. The thermal flow induced by optical tweezers dominates the growth acceleration at the interface. Furthermore, optical tweezers are used to create a local growth peak at the growing front, which is used to study the preferential incorporation positions of incoming particles.The results show that the particles surfed with a strong Marangoni flow tend to fill the gap and smoothen the steep peaks. When the peak is smooth, the incoming particles incorporate the crystal homogeneously at the growing front.     

Interatomic Interaction at the Aluminum–Fullerene C60 Interface

Journal of Experimental and Theoretical Physics - We propose a model of interaction between aluminum and carbon atoms at the Al/C60 interface. The binding energy and the fullerene position of the...