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Notes: The symmetry-predicted nonzero components of the piezoelectric coefficient, dielectric constant, and elastic compliance matrices have been determined on poly(vinylidene fluoride/trifluoroethylene)(75/25) copolymer at room temperature and a frequency of 500 Hz. The temperature dependence of each of the complex piezoelectric coefficients and complex dielectric constants has been measured in the temperature range of −100 to 65 °C. The frequency dependence of these coefficients has also been measured at room temperature. It is found that the relaxation observed in the tensile piezoelectric coefficients of this material is different from that of the dielectric constants, whereas the relaxation of the piezoelectric shear constants shows behavior similar to that of the dielectric constants.

Notes: Ferrite plating facilitates the formation of polycrystalline spinel films in an aqueous solution below 100 °C. The plating temperature can be extended up to 200 °C when the pressure of the reaction solution is kept high (15–20 kgf/cm2). We call this "hydrothermal ferrite plating,'' by which solubility limit of Ni in Fe3−xNixO4 increases much, from x=0.3 (by conventional ferrite plating at 90 °C) to x=0.93.1 In this paper we describe preparation of Fe3−xCoxO4 films by the hydrothermal ferrite plating at T=120–200 °C and p=15–40 kgf/cm2, and report their structural and magnetic properties. Plating for 1 h, we obtained films about 1 μm in thickness, which are polycrystalline with no preferential crystal orientation as observed by x-ray diffraction. The solubility limit of Co, which is x=0.6 at 90 °C, increases to x=1.3 at 180 °C. The solubility limit of Co is higher than that of Ni, which may be because Ni tends to keep 2+ state in the spinel structure, while Co can take both 2+ and 3+ states. When prepared at 200 °C, the saturation magnetization of the films are smaller than that reported for bulk samples, though both agree when the films are prepared at 90 °C.2 This suggests that Co is oxidized to 3+ state even when x〈1.0 as large as the Fe3−xCoxO4 films are prepared in the hydrothermal conditions. We found that adding CH3COONH4 into the reaction solution as a pH buffer improves the smoothness of the film surface.

Notes: In general, the piezoelectric ceramic and polymer in a 1–3 type composite will have different deformations when subjected to an external field. How each component deforms, to a large extent, determines the performance of the composite. Based on the force equilibrium condition, an elastic model is introduced to analyze the strain profiles of these composites, and the theoretical results are in quantitative agreement with the strain profiles measured on several composites using a double beam ultradilatometer. The results obtained provide quantitative information on how various parameters in a composite affect the performance of the composite. Furthermore, a scheme is proposed for evaluating the strain profile of a 1–3 type composite under a hydrostatic pressure using a double beam dilatometer.

Notes: Polycrystalline NixZnyFe3−x−yO4 films were prepared by the spin-spray ferrite plating method on oxygen-plasma-treated and non-plasma-treated glass substrates from an aqueous solution at 96 °C. The oxygen-plasma treatment increased film adhesion to the substrate, and enabled films thicker than 15 μm to be grown. A film with composition of (x+y)=0.75 had a saturation magnetization of 103 emu/g, a coercive force of ∼7 (Oe), ferromagnetic resonance linewidth (perpendicular to the film plane) of 80 (Oe), and resistivity of 106 Ω cm. These results compare favorably with ceramics of NiZn ferrite on the market.

Notes: Inhomogeneous displacement profiles have been derived for a single-rod composite and a single-tube 1-3 ceramic-polymer composite under both uniaxial and hydrostatic stress. The effective piezoelectric constants for the composites have been derived in terms of the ceramic content, the piezoelectric and elastic constants of each component, and the aspect ratio of the ceramic rod. The stress concentration inside both phases is derived from the calculated inhomogeneous displacement profiles. It is found that only a finite portion of the polymer in the vicinity of the ceramic-polymer interface actually contributes to the stress transfer, and the induced additional stress on the ceramic also has a higher magnitude near the interface. The theoretical results quantitatively predict the performance of a given 1-3 structure, and can be used to optimize the design parameters, such as ceramic content, aspect ratio of the ceramic rods, rod geometry and rod arrangement, resin hardness, etc., for 1-3 structures designed for specific purposes.

Notes: The stimulated emission pumping (SEP) process has been detected by means of a newly developed zero-background scheme based upon the Doppler-free technique of degenerate four-wave mixing (DFWM) spectroscopy. Rotationally resolved SEP-DFWM spectra recorded for the (02000) vibrational level of CS2 X˜ 1∑+g exhibit signal-to-noise ratios approaching 1000:1.

Notes: We investigated the potential energy surface for the H2O⋅⋅⋅H interaction in the van der Waals well region. Calculations were carried out using the Møller–Plesset second- and fourth-order perturbation theory in a [12s,7p,2d]→(6s,5p,2d) basis set for the O atom, and [6s,2p,1d]→(5s,2p,1d) for the H atoms. Basis set and superposition error effects were analyzed to gauge the reliability of the calculated potential. The potential was investigated in five physically distinct directions. The deepest potential well was found in the H2O molecular plane 3.30–3.45 A(ring) from the H2O center of mass, near the H end of the OH bond. The following parameters are suggested for the spherically averaged potential: well depth 53±6 cm−1; minimum distance from the center of mass 3.25–3.40 A(ring).

Notes: Condensation dynamics and structure of low temperature ≤100 K amorphous ices is studied using the classical trajectory simulation technique. Specifically, classical equations of motion are solved for a sequence of H2O molecules impinging at random on an initial nucleus of ten water molecules. The sticking probability to the cluster is found to be unity. Using this technique we accumulated three amorphous clusters of 100–300 water molecules. The analysis of the results included collision dynamics and molecular structure. Upon collision with the cluster, the impinging H2O molecule forms typically two hydrogen bonds. The two new bonds are almost always asymmetric, i.e., one bond is via an O atom of the new molecule, and the other via one of its H atoms. We identified two distinct types of collision trajectories—"simple'' trajectories and "complex'' ones. In a simple trajectory, a new molecule is attached to the surface, without disrupting the preexisting hydrogen bond network in the cluster. In a complex trajectory, the preexisting bond network is modified significantly during the collision. Up to ∼15 hydrogen bonds can be changed (formed or destroyed) during such a trajectory; and the spatial extent of the changes can be as large as ∼20 A(ring).The complex trajectories comprise 60%∼70% of all the collision trajectories. Thus, the hydrogen bond network evolves continuously during the growth of the ice sample; the net trend being towards the four coordinated molecular configuration around each molecule. The average coordination number of a molecule in the final clusters is 3.5∼3.7, despite the fact that most of the water molecules are on the exposed surface of the cluster. The main features of the local molecular structure in the clusters are (a) ordering of OO and OH distances within hydrogen bonds (b) very significant disorder in O–O–O angles between adjacent hydrogen bonds; the width of the O–O–O angle distribution is ∼40°. The molecular structure seems to be closely related to that of liquid water. The experimental electron diffraction patterns of amorphous clusters are reproduced very well by our models. Comparison was also made with the radial distribution functions derived for bulk amorphous ice from x-ray and neutron diffraction experiments. Reasonable agreement was obtained within the range (approximately-less-than)4 A(ring), while at larger distances finite size effects become important.

Notes: We investigate the density-orientation profile of a polar liquid in planar interfaces. This liquid, which represents one side of the interface, is coupled with a second medium which can be an ideal solid characterized only by its dielectric constant or another polar liquid. We derive an expression for the asymptotic behavior of the profile which is exact provided the molecules interact by an additive pairwise potential. As a consequence of the renormalization of bonds, we show that the result does not depend explicitly on the particular form of the short range part of the pair potential. Moreover, the asymptotic behavior of the profile does not depend on the physical origin of the second medium provided it behaves as a dielectric. In addition, we show that the result remains exact in presence of a soft wall and can be extended to the liquid–vapor interface. As established in a previous paper, we show that the isotropic part of the profile is intimately connected with the electrostriction phenomena observed in bulk phase when a strong electrical field is applied. In order to clarify this point, we derive the expression of the electrostriction constant from the relation density-one body direct correlation function which has been used for studying the profile. We point out that the electrostriction and the long tail of the profile represent two ways for investigating some orientational components of the triplet direct correlation function in bulk phase. More generally, we show that the triplet direct correlation function largely determines the orientational structure of the profile.