Matrix influence on the piezoelectric properties of piezoelectric ceramic/polymer composite exhibiting particle alignment

This study was addressed to the influence of an electric field strength applied at fabrication process and matrix properties, such as the dielectric constant and the Young's modulus, on “pseudo‐1‐3 piezoelectric ceramic/polymer composite” in order to further enhance the piezoelectricity of that. The pseudo‐1‐3 piezoelectric ceramic/polymer composite consists of linearly ordered piezoelectric ceramic particles in polymer material. Silicone gel, silicone rubber, urethane rubber, and poly‐methyl‐methacrylate, which exhibit different dielectric constants and Young's modulus, were used as matrices to evaluate the matrix influence. The piezoelectricity of the pseudo‐1‐3 piezoelectric ceramic/polymer composite was evaluated using the piezoelectric strain constant d₃₃. The d₃₃ is one of the indices of the piezoelectric properties for piezoelectric materials. As a result, it was confirmed that d₃₃ of the pseudo‐1‐3 piezoelectric ceramic/polymer composite increased with the increase of the electric filed strength applied at fabrication process, though, it reached a constant value at a certain strength value. Further it was confirmed that dielectric constant of the matrix had a small influence on d₃₃ of the pseudo‐1‐3 piezoelectric ceramic/polymer composite, however, in case of matrix of lower Young's modulus, d₃₃ was increase. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41817.     

Anatase Sol Prepared from Peroxotitanium Complex Aqueous Solution Containing Niobium or Vanadium

Niobium- or vanadium-doped anatase sols were prepared by hydrothermal treatment of 0.1 mol/dm³ peroxotitanium complex aqueous solutions dissolving 0–10 mol% niobium or vanadium at 100°C for 8 h. Niobium-doping caused the increase of lattice constants of anatase and the shape change of anatase crystal from spindle-like to cubic-like structure, but no change of the optical absorbance. Vanadium-doping caused the decrease of lattice constant of c -axis, the miniaturization of anatase crystal and the increase of optical absorbance at the wavelength from 350–700 nm.     

The effect of ionic cross-links on the deformation behavior of homoblends made of poly(styrene-co-styrenesulfonic acid) and poly(styrene-co-4-vinylpyridine)

Deformation behavior of stoichiometric blends made from poly(styrene-co-styrenesulfonic acid) (SPS) and poly(styrene-co-4-vinylpyridine) (SVP) was investigated by TEM observation of strained thin films. An FTIR investigation revealed that ionic cross-links were formed between the component polymers upon blending due to intermolecular ion-ion interactions, which arose from proton transfer from sulfonic acid groups to pyridine groups. TEM observations indicate that the deformation mode of the blends changed from crazing only to crazing plus shear deformation, with the shear contribution becoming larger, as the ion content in the blends increased. Such changes in deformation mode can be understood as arising from an increase in the ‘effective’ strand density due to the formation of ionic cross-links upon blending. It was also found that the ionic cross-links via pyridinium cation/sulfonate anion ion pairs were more effective in inducing the transition of deformation mode than ionic cross-links via -SO₃⁻/Na⁺ or -SO₃⁻/Ca²⁺ ion pairs.     

Chemical potentials of oxygen for three-phase assemblages of CaSiO3(s) + Ca3Si2O7(s) + {CaO + SiO2 + FexO} melt and Ca3Si2O7(s) + Ca2SiO4(s) + {CaO + SiO2 + FexO} melt

By employing an electrochemical technique involving stabilized zirconia as solid electrolyte and Mo + MoO₂ mixture as reference electrode, the equilibrium oxygen partial pressures for three-phase assemblages of CaSiO₃(s) + Ca₃Si₂O₇(s) + {CaO + SiO₂ + Fe_xO} melt and Ca₃Si₂O₇(s) + Ca₂SiO₄(s) + {CaO + SiO₂ + Fe_xO} melt were determined as: - log {P_O2 (CS + C₃S₂ + L)/bar} = - 3.22 13000/(T/K) ± 0.05 - log {P_O2 (C₃S₂ + C₂S + L)/bar} = - 0.92 16400/ (T/K) ± 0.04. respectively, where CS, C₃S₂ and C₂S indicate CaSiO₃(s), Ca₃Si₂O₇(s). and Ca₂SiO₄(s), respectively.     

Computation of mutual entropy in quantum markov chains

There are several damping phenomena in quantum optics. Such phenomena have been usually explained by open systems. In statistical physics, open system dynamics have been used to study the irreversibility and the approach to equilibrium. In this paper, the dynamical change of the mutual entropy for an open system, frequently studied in the quantum optics literature, is rigorously computed through a model of quantum Markov chain. In particular, the concrete formula of Stinespring expression for such a model is obtained and applied to the derivation of the mutual entropy, and some computational results are presented.     

Critical heat flux on a flat plate heater located at the middle of a duct in forced flow of pressurized He II

Critical heat fluxes (CHFs) were measured for two types of rectangular ducts containing horizontal flat plate heaters. One has the flat plate heater of 6 mm wide and 20 mm long located on the inner lower wall at 50 mm from the inlet. The other duct has two horizontal flat plates of 6 mm wide and 20 mm long on inner upper and lower walls at 50 mm from the inlet. The equation of CHF for the forced convection containing a new nondimensional-parameter m introduced in order to calculate cross-sectionally averaged liquid temperature at the center of the duct was derived based on two fluid model, ordinary convection theorem and experimental results. It was confirmed that this correlation can describe not only the author's data on the duct but also other worker's data for channels with different shapes and sizes.     

Growth of Potassium Titanate Fibers in Flowing N2 Gas

The length of potassium titanate fibers produced by several conventional methods averages 50 μm, with a maximum of 100 μm. Extremely long fibers (most >1000 μm long) were obtained by calcination in N₂ gas flowing at 5.2×10^-4 m/s.     

InxGa1−xAs ohmic contacts to n-type GaAs with a tungsten nitride barrier

Significant reduction of the contact resistance of In_0.7Ga_0.3As/Ni/W contacts (which were previously developed by sputtering in our laboratory) was achieved by depositing a W₂N barrier layer between the Ni layer and W layer. The In_0.7Ga_0.3 As/Ni/W₂N/W contact prepared by the radio-frequency sputtering technique showed the lowest contact resistance of 0.2 Ωmm after annealing at 550°C for 10 s. This contact also provided a smooth surface, good reproducibility, and excellent thermal stability at 400°C. The polycrystalline W₂N layer was found to suppress the In diffusion to the contact surface, leading to improvement of the surface morphology and an increase in the total area of the In_xGa−As between metal and the GaAs substrate. These improvements are believed to reduce the contact resistance.