CaCu_3Ti_4O_12/CaTiO_3 Composite Dielectrics: A Ba/Pb-free Ceramics with High Dielectric Constants

We have measured dielectric properties of Ca$_{1+x}$Cu$_{3-x}$Ti$_4$O$_{12}$ ($x$ = 0, 0.1, 0.5, 1, 1.5, 2, 2.9 and 3), and have found that Ca$_2$Cu$_2$Ti$_4$O$_{12}$ (a composite of CaCu$_3$Ti$_4$O$_{12}$ and CaTiO$_3$) exhibits a high dielectric constant of 1800 with a low dissipation factor of 0.02 below 100 kHz from 220 to 300 K. These are comparable to (or even better than) those of the Pb/Ba-based ceramics, which could be attributed to a barrier layer of CaTiO$_3$ on the surface of the CaCu$_3$Ti$_4$O$_{12}$ grains. The composite dielectric ceramics reported here are environmentally benign as they do not contain Ba/Pb.Comment: 4 pages, 4 figures, Appl. Phys. Lett. (scheduled on July 25, 2005

The influence of diluter system on polymer-stabilised blue-phase liquid crystals

In the present work, diluter effects on the phase transition temperatures and electro-optical properties of the polymer-stabilised blue-phase liquid crystals with microsecond respond time have been carried out. The temperature range of polymer-stabilised blue-phase samples broadened over 50 K including room temperature. By increasing the concentration of diluter, the faster response time is obtained, but Kerr constant become smaller. These values are still two orders of magnitude larger than conventional Kerr materials such as nitrobenzene. The major bottleneck is the increased operating voltage. Hysteresis is sensitive to the diluter concentration and is slightly small for polymer network systems. For next-generation display technology, an optimal concentration of diluter plays a crucial role to a proper balance between response time and operation voltage

Effects of Dielectric Inhomogeneity and Electrostatic Correlation on the Solvation Energy of Ions in Liquids

© 2018 American Chemical Society. Electrolytes often involve the spatially varying dielectric response of liquids and electrostatic correlation. Nevertheless, the complexity of their synergistic effects complicates our understanding of ion solvation and often limits theoretical approaches. Thus, we develop a Ginzburg-Landau-like (GL) theory that simultaneously considers these two features. We derive the modified Born solvation energy of ions, which accounts for the effect of saturated dipoles near the ions on the solvation energy, which is in good agreement with experimental data for different ionic charges and even for some selected liquid mixtures. Moreover, we consider the phase diagram of a mixture of polyelectrolyte and uncharged polymer and that of a mixture of ionic liquid and uncharged polymer. The GL theory encompasses the results of the previous mean-field theories, accounting for fluctuations of the electrostatic potentials and hence serves as a simple alternative approach to dielectrically inhomogeneous media