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Irregularly shaped (IRS) particles widely exist in many engineering and industrial fields. The macro physical and mechanical properties of the particle system are governed by the interaction between the particles in the system. The interaction between IRS particles is more complicated because of their complex geometric shape with extremely irregular and co-existed concave and convex surfaces. These particles may interlock each other, making the sliding and friction of IRS particles more complex than that of particles with regular shape. In order to study the interaction of IRS particles more efficiently, a refined method of constructing discrete element model based on computed tomography scanning of IRS particles is proposed. Three parameters were introduced to control the accuracy and the number of packing spheres. Subsequently, the inertia tensor of the IRS particle model was optimized. Finally, laboratory and numerical open bottom cylinder tests were carried out to verify the refined modeling method. The influence of particle shape, particle position, and mesoscopic friction coefficient on the interaction of particles was also simulated. It is noteworthy that with the increase of mesoscopic friction coefficient, the fluidity of IRS particle assembly decreases, and intermittent limit equilibrium state may appear. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Dense (1− x)Ca(Mg1/3Ta2/3)O3/ xCaTiO3 ceramics (0.1≤ x≤0.9) were prepared by a solid-state reaction process. The crystal structures and microstructures were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Single-phase solid solutions were obtained in the entire composition range. Long-range 1:2 ordering of B-site cations and oxygen octahedra tilting lead to the monoclinic symmetry with space group P21/ c for x=0.1. For x above 0.1, the long-range ordering was destroyed and the crystal structure became the orthorhombic with space group Pbnm. The microwave dielectric properties showed a strong dependence on the composition and microstructure. The dielectric constant and temperature coefficient of resonant frequency increased nonlinearly as the CaTiO3 content increased while the Qf values decreased approximately linearly. Good combination of microwave dielectric properties was obtained at x=0.45, where ℇr=45.1, Qf=34 800 GHz, and τf=17.4 ppm/°C. [ABSTRACT FROM AUTHOR]

The dielectric characteristics of BaBi2Nb2O9, BaBi4Ti4O15, BaBi8Ti7O27, and La-substituted SrBi4Ti4O4 were investigated to discuss their ferroelectric phase transition and relaxor behaviors. BaBi2Nb2O9 showed typical relaxor behaviors, and a shift of Tm with increasing frequency was observed in BaBi4Ti4O15 and SrBi4− xLa xTi4O15 ( x=0.8, 1.0) but they underwent a real paraelectric–ferroelectric phase transition on zero-field cooling, while BaBi8Ti7O27 showed a normal ferroelectric nature. The reduced concentration and weakened coupling of the dipoles related to A-site bismuth are believed to be responsible for the appearance of short-range electric ordering and the relaxor behaviors in these bismuth layer-structured compounds. [ABSTRACT FROM AUTHOR]

Microcavity organic light-emitting diodes (OLEDs) with ITO distributed Bragg reflectors (DBRs) were proposed. For the 6.5-period DBR electrode, the Bragg reflectivity and sheet resistance of 92.3% and 30 Ω/ square were obtained. In addition, the full width at half maximum of the electroluminescence spectra of the microcavity OLED was <7 nm and the enhancement of the optical intensity was 4.6 times higher in amplitude than that of the non-cavity OLED. [ABSTRACT FROM AUTHOR]

The dielectric characteristics of BaBi2Nb2O9, BaBi4Ti4O15, BaBi8Ti7O27, and La-substituted SrBi4Ti4O4 were investigated to discuss their ferroelectric phase transition and relaxor behaviors. BaBi2Nb2O9 showed typical relaxor behaviors, and a shift of Tm with increasing frequency was observed in BaBi4Ti4O15 and SrBi4− xLa xTi4O15 ( x=0.8, 1.0) but they underwent a real paraelectric–ferroelectric phase transition on zero-field cooling, while BaBi8Ti7O27 showed a normal ferroelectric nature. The reduced concentration and weakened coupling of the dipoles related to A-site bismuth are believed to be responsible for the appearance of short-range electric ordering and the relaxor behaviors in these bismuth layer-structured compounds. [ABSTRACT FROM AUTHOR]