Ultrasonic, pressure-volume, and shock wave measurements of NaCl are reviewed, with the purpose of representing as much as possible within a single theoretical framework, A large portion of the data is consistent, to within reasonable uncertainties, with the Eulerian formulation of finite strain, in the BE2 form. This contains three parameters, of which two, K0 and K0′, are obtainable from single-crystal ultrasonic measurements, while the third, K0″, may be found with the aid of shock wave data. The combination of the values of Spetzler et al. (1972a) with the isotherm of Fritz et al. (1971) gives an equation of state consistent with the pressure-volume measurements to 300 kbar, to within a kilobar or two. There remain small but possibly significant discrepancies with the high-precision measurements of linear change at low pressures. Various two-parameter isotherms are also examined and found to fail either at low or at high compressions: While other three-parameter forms may be fitted to the data, they do not afford a satisfactory general treatment of wave propagation. Finite strain theory is applied to project the effective elastic coefficients of single-crystal NaCl to 270 kbar. The anisotropy index, 2B44(B11–B12), falls from 0.7 at P = 0 to 0.12 at 270 kbar, and the usual methods of averaging to find the properties of a quasi-isotropic aggregate diverge increasingly as pressure increases. The methods of Kroner and of Peresada give fair agreement with recent measurements of velocities in NaCl aggregates to 270 kbar.

Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300°K

Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers...

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

Study of flexible nanodielectric materials (FNDMs) with high permittivity is one of the most active academic research areas in advanced functional materials. FNDMs with excellent dielectric properties are demonstrated to show great promise as energy-storage dielectric layers in high-performance capacitors. These materials, in common, consist of nanoscale particles dispersed into a flexible polymer matrix so that both the physical/chemical characteristics of the nanoparticles and the interaction between the nanoparticles and the polymers have crucial effects on the microstructures and final properties. This review first outlines the crucial issues in the nanodielectric field and then focuses on recent remarkable research developments in the fabrication of FNDMs with special constitutents, molecular structures, and microstructures. Possible reasons for several persistent issues are analyzed and the general strategies to realize FNDMs with excellent integral properties are summarized. The review further highlights some exciting examples of these FNDMs for power-energy-storage applications.

Flexible Nanodielectric Materials with High Permittivity for Power Energy Storage

Dendron-mediated self-assembly, disassembly, and self-organization of complex systems have been investigated. The most ideal building blocks would need to display shape persistence in solution and in the solid state, since only this feature provides access to the use of complementary methods of structural analysis. Most supramolecular dendrimers are chiral even when they are constructed from nonchiral building blocks and are equipped with mechanisms that amplify chirality. This poses additional challenges associated with the understanding of the structural origin of chirality in different supramolecular structures through combinations of structural analysis methods. While many supramolecular structures assembled from dendrimers and dendrons resemble some of the related morphologies generated from block-copolymers, they are much more complex and are not determined by the volume ratio between the dissimilar parts of the molecule.

Dendron-Mediated Self-Assembly, Disassembly, and Self-Organization of Complex Systems

A calculation of the equation of state for NaCl from a Mie‐Gruneisen equation was repeated using more accurate values of the zero‐pressure compressibility. It was also extended to KCl and CsCl. An analysis of this approach to pressure calibration indicates that it will yield pressures with about the same accuracy as can be presently achieved by experimental measurements above 25 kbar, and thus furnishes a temporary practical pressure scale.

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High‐Pressure Equation of State for NaCl, KCl, and CsCl

Micro/nanolayer coextrusion was used to fabricate polycarbonate (PC)/poly(vinylidene fluoride) (PVDF) layered films with significantly reduced dielectric losses while maintaining high energy density. The high-field polarization hysteresis was characterized for layered films as a function of PVDF layer thickness (6000 to 10 nm) and composition (10 to 70 vol % PVDF), and was found to decrease with decreasing layer thickness and PVDF content. To gain a mechanistic understanding of the layer thickness (or nanoconfinement) effect, wide-angle X-ray diffraction, polarized Fourier transform infrared spectroscopy, and broadband dielectric spectroscopy were employed. The results revealed that charge migration, instead of dipole flipping, was responsible for the hysteresis in multilayered films. The absence of PVDF dipole-flipping was attributed to the nonuniform electric field distribution in the layered structure, where the field in PVDF layers were calculated to be significantly lower than that in PC layers due t...

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Reduction of Dielectric Hysteresis in Multilayered Films via Nanoconfinement

Pressure and temperature derivatives of the elastic constants of caF2 and BaF2

Pressure derivatives of the elastic constants of NaCl and KCl at 295°K and 195°K

Interfacial polarization and layer thickness effect on electrical insulation in multilayered polysulfone/poly(vinylidene fluoride) films

The 1000‐Hz 300°K dielectric constants were measured for crystalline α‐quartz, sapphire, MgF2, and MgO, and polycrystalline sapphire (Lucalox), magnesium fluoride (IRTRAN 1), and magnesium oxide (IRTRAN 5). The measurements were performed using the method of substitution (two‐fluid method). The results are as follows: single‐crystal α‐quartz, es∥=4.6368±0.001 and es⊥=4.5208±0.001; single‐crystal sapphire, es∥ = 11.589±0.005 and es⊥=9.395±0.005; polycrystalline sapphire (Lucalox), es=10.154±0.007; single‐crystal MgF2, es∥ =4.826±0.01 and es⊥=5.501±0.01; polycrystalline MgF2 (IRTRAN 1), es=5.289±0.001; single‐crystal MgO, es=9.830 ±0.001; and polycrystalline MgO (IRTRAN 5), es=9.833±0.001, where es∥ and es⊥ are the dielectric constants parallel and perpendicular, respectively, to the c axis.

Donald E. Schuele

Papers

Reduction of Dielectric Hysteresis in Multilayered Films via Nanoconfinement

Pressure and temperature derivatives of the elastic constants of caF2 and BaF2

Pressure derivatives of the elastic constants of NaCl and KCl at 295°K and 195°K

Interfacial polarization and layer thickness effect on electrical insulation in multilayered polysulfone/poly(vinylidene fluoride) films

Low‐frequency dielectric constants of α‐quartz, sapphire, MgF2, and MgO