Solvation Effects on the Dielectric Constant of 1 M LiPF6 in Ethylene Carbonate: Ethyl Methyl Carbonate 3:7

In this communication we report the dielectric constant of 1 M LiPF6 in EC:EMC 3:7 w/w (ethylene carbonate/ethyl methyl carbonate) in addition to neat EC:EMC 3:7 w/w. Using three Debye relaxations, the static permittivity value, or dielectric constant, is extrapolated to 18.5, which is compared to 18.7 for the neat solvent mixture. The EC solvent is found to strongly coordinate with the Li+ cations of the salt, which results in a loss of dielectric contribution to the electrolyte. However, the small amplitude and large uncertainty in relaxation frequency for EMC cloud definitive identification of the Li+ solvation shell. Importantly, the loss of the free EC permittivity contribution due to Li+ solvation is almost completely balanced by the positive contribution of the associated LiPF6 salt, demonstrating that a significant quantity of dipolar ion pairs exists in 1 M LiPF6 in EC:EMC 3:7.

EFFECT OF DC BIAS ON DIELECTRIC RESPONSE IN RELAXOR FERROELECTRIC TERPOLYMER FILMS

The permittivity as a function of temperature and dc bias in the poly(vinylindene fluoride-trifluorethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer was measured and analyzed using both the Vogel–Fulcher and universal Curie–Weiss law. The decreased permittivity with increasing dc bias has been observed. The lower permittivity in dc bias is due to the suppressed diffusion of phase transition rather than the nonlinear dielectric contribution. Furthermore, the suppression of phase diffusion can be explained by the molecular conformation conversion in dc bias.

High permeability and high permittivity heterostructures for the miniaturization of Radiofrequency components

This paper discusses on the miniaturization of radiofrequency (RF) front-end components such as half-wavelength resonators based on new magneto-dielectric heterostructures combining high permeability (µ = 150–250) and high permittivity (ε = 18–150). Size reduction is evaluated by means of 2-cm-long coplanar waveguides realized with silicon technology and having a resonance frequency of about 3 GHz. The experimental results show a physical length reduction of 11.2% due to the dielectric contribution (ε = 18) and 14.8% by cumulating dielectric and magnetic effects (ε = 18 and µ = 150). These results are significant with respect to the moderate thickness of the preliminary material used here (only 150 nm). In a second part, a predictive model is proposed with µ and ε as variables. When adjusting the material properties in a realistic way (µ = 250 and ε = 150), the model predicts size reduction of ~50% for the same thickness. Larger values can be expected with increasing the film thickness.