The demand for dielectric capacitors with higher energy-storage capability is increasing for power electronic devices due to the rapid development of electronic industry. Existing dielectrics for high-energy-storage capacitors and potential new capacitor technologies are reviewed toward realizing these goals. Various dielectric materials with desirable permittivity and dielectric breakdown strength potentially meeting the device requirements are discussed. However, some significant limitations for current dielectrics can be ascribed to their low permittivity, low breakdown strength, and high hysteresis loss, which will decrease their energy density and efficiency. Thus, the implementation of dielectric materials for high-energy-density applications requires the comprehensive understanding of both the materials design and processing. The optimization of high-energy-storage dielectrics will have far-reaching impacts on the sustainable energy and will be an important research topic in the near future.

This paper describes a sintering technique for ceramics and ceramic-based composites, using water as a transient solvent to effect densification (i.e. sintering) at temperatures between room temperature and 200 °C. To emphasize the incredible reduction in sintering temperature relative to conventional thermal sintering this new approach is named the "Cold Sintering Process" (CSP). Basically CSP uses a transient aqueous environment to effect densification by a mediated dissolution-precipitation process. CSP of NaCl, alkali molybdates and V2 O5 with small concentrations of water are described in detail, but the process is extended and demonstrated for a diverse range of chemistries (oxides, carbonates, bromides, fluorides, chlorides and phosphates), multiple crystal structures, and multimaterial applications. Furthermore, the properties of selected CSP samples are demonstrated to be essentially equivalent as samples made by conventional thermal sintering.

A series of 0−3 metal oxide−polyolefin nanocomposites are synthesized via in situ olefin polymerization, using the following single-site metallocene catalysts: C 2-symmetric dichloro[rac-ethylenebisindenyl]zirconium(IV), Me2Si( t BuN)(η5-C5Me4)TiCl2, and (η5-C5Me5)TiCl3 immobilized on methylaluminoxane (MAO)-treated BaTiO3, ZrO2, 3-mol %-yttria-stabilized zirconia, 8-mol %-yttria-stabilized zirconia, sphere-shaped TiO2 nanoparticles, and rod-shaped TiO2 nanoparticles. The resulting composite materials are structurally characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 13C nuclear magnetic resonance (NMR) spectroscopy, and differential scanning calorimetry (DSC). TEM analysis shows that the nanoparticles are well-dispersed in the polymer matrix, with each individual nanoparticle surrounded by polymer. Electrical measurements reveal that most of these nanocomposites have leakage current densities of ∼10−6−10−8 A/cm2; relative permittivities increase as the nanoparticle volume fraction increases, with measured values as high as 6.1. At the same volume fraction, rod-shaped TiO2 nanoparticle−isotactic polypropylene nanocomposites exhibit significantly greater permittivities than the corresponding sphere-shaped TiO2 nanoparticle−isotactic polypropylene nanocomposites. Effective medium theories fail to give a quantitative description of the capacitance behavior, but do aid substantially in interpreting the trends qualitatively. The energy storage densities of these nanocomposites are estimated to be as high as 9.4 J/cm3.