Determining the dielectric constant of injection-molded polymer-matrix nanocomposites filled with barium titanate.

Barium titanate (BTO) is a ferroelectric perovskite with potential in energy storage applications. Previous research suggests that BTO dielectric constant increases as nanoparticle diameter decreases. This report recounts an investigation of this relationship. Injection-molded nanocomposites of 5 vol% BTO nanoparticles incorporated in a low-density polyethylene matrix were fabricated and measured. Finite-element analysis was used to model nanocomposites of all BTO sizes and the results were compared with experimental data. Both indicated a negligible relationship between BTO diameter and dielectric constant at 5 vol%. However, a path for fabricating and testing composites of 30 vol% and higher is presented here. SUPPLEMENTARY MATERIAL: The supplementary material for this article can be found at 10.1557/mrc.2020.69.

Clean and highly ordered graphene synthesized in the gas phase.

We report that the substrate-free gas-phase graphene synthesis method produces clean and highly ordered graphene sheets that are similar in quality to the graphene obtained through the mechanical exfoliation of highly oriented pyrolytic graphite.

Direct imaging of soft-hard interfaces enabled by graphene.

Direct imaging of surface molecules and the interfaces between soft and hard materials on functionalized nanoparticles is a great challenge using modern microscopy techniques. We show that graphene, a single atomic layer of sp(2)-bonded carbon atoms, can be employed as an ultrathin support film that enables direct imaging of molecular layers and interfaces in both conventional and atomic-resolution transmission electron microscopy. An atomic-resolution imaging study of the capping layers and interfaces of citrate-stabilized gold nanoparticles is used to demonstrate this novel capability. Our findings reveal the unique potential of graphene as an ideal support film for atomic-resolution transmission electron microscopy of hard and soft nanomaterials.

Substrate-free gas-phase synthesis of graphene sheets.

We present a novel method for synthesizing graphene sheets in the gas phase using a substrate-free, atmospheric-pressure microwave plasma reactor. Graphene sheets were synthesized by passing liquid ethanol droplets into an argon plasma. The graphene sheets were characterized by transmission electron microscopy, electron energy loss spectroscopy, Raman spectroscopy, and electron diffraction. We prove that graphene can be created without three-dimensional materials or substrates and demonstrate a possible avenue to the large-scale synthesis of graphene.