Electrical and dielectric properties of barium titanate – polydimethylsiloxane nanocomposite with 0-3 connectivity modified with carbon nanotube (CNT)

Abstract

This study explored the preparation and electrical properties of 0–3 barium titanate/polydimethylsiloxane nanocomposites by dispersing barium titanate nanoparticles (BaTiO₃; BT) into the polydimethylsiloxane (PDMS) matrix phase. The effect of barium titanate nanoparticles on electrical properties has been investigated systematically, and the relative permittivity of nanocomposites was found to increase significantly with increasing barium titanate content. Different theoretical models were used to predict the dielectric constant of these composites and compare their experimental value with the theoretical value in order to find an appropriate equation. The result indicated that the dielectric properties of composites are influenced not only by relative permittivity of the components but also dependence on interactions between ceramics and polymers. Furthermore, the preparation and dielectric properties of BT/PDMS nanocomposites modified with carbon nanotube (CNT) were also studied. The dielectric results demonstrate that adding CNT can enhance the relative permittivity of the BT/PDMS composite via improvement of dispersion and distribution of the BT nanoparticles in the PDMS matrix phase. Moreover, the electrical outputs from the BT/PDMS/CNT nanocomposites generator were measured under periodic knocking. The nanocomposites innovatively expand the feasibility of self-powered energy systems for smart sensor and energy harvesting applications.     

Synthesis and phase evolution of electrospun antiferroelectric lead zirconate (PbZrO3) nanofibers

Lead zirconate (PbZrO₃; PZO) fibers were synthesized by the electrospinning method using a solution that contained 5 wt% poly(ethylene oxide) (PEO) in ethanol and a sol–gel solution of PZO. Some parameters varied, for example, the ratio between PEO and PZO, concentrations of the precursor solution, flow rate, and calcination temperature. The as-spun and calcined PZO/PEO composite fibers were characterized by TG-DTA, X-ray diffraction, FT-IR, SEM and TEM. PZO fibers were obtained successfully with a well-developed perovskite structure after as-spun PZO/PEO composite fibers were calcined using the PZO/PEO volume ratio of 10:3 at a PZO concentration of 1.0 M at 650 °C for 4 h. Stable nanofibers were produced with an average diameter of 300 ± 64 nm. Additionally, the PZO fibers showed a Curie temperature that rose by nearly 13 °C, when comparing with a normal PZO particle.     

Synthesis of BaTiO3@TiO2-sheet Core-Shell Structured Nanocomposites

Abstract

Core-shell structure nanocomposites have been of interest, as they can exhibit unique properties arising from the combination of peculiar characteristics of each component. In this research, core-shell structured nanocomposites, comprising barium titanate (BaTiO₃; BT) nanoparticles as the core and titanate (TiO₂) nanosheets as the shell, were prepared. The surface of barium titanate (BT) nanoparticles was modified chemically by hydrogen peroxide (H₂O₂) to create hydroxyl groups. TiO₂ nanosheets were deposited on the surface of the functionalized BT core, via alternate adsorption with oppositely charged polyelectrolyte poly(diallyl dimethylammonium) (PDDA) cations to produce an ultrathin TiO₂ shell layer that encapsulates BaTiO₃ nanoparticles. The structure of the core-shell particles was investigated in order to illustrate their formation mechanisms. Furthermore, this work reported the advance in utilizing a core-shell nanostructure to enhance relative permittivity and maintaining a low loss of polymer nanocomposites. A significant improvement in relative permittivity is attributed to the TiO₂ shell, which acts as polarizable dipoles and consequently enhances interfacial polarization. The results indicated that the structure of core-shell nanocomposites is attractive as a novel structural building block for fabricating novel materials and electronic devices.     

The Possible Positive Mechanisms of Pirenoxine in Cataract Formation

Cataract is the leading cause of blindness worldwide. A diverse range of medication has been invented to prevent or treat cataract. Pirenoxine (PRX), a drug with strong antioxidant properties, has been used topically to treat cataract, and there is much evidence to demonstrate the beneficial effects of PRX on lens opacity from in vitro and in vivo models. In clinical use, PRX has been prescribed worldwide by ophthalmologists for over six decades; however, there is still controversy with regard to its efficacy, and thus PRX remains an off-label use for cataract treatment. This comprehensive review summarizes and discusses evidence pertinent to the mechanisms of PRX and its efficacy mainly on cataract models. The issues that have been deemed uncertain over the six-decade use of PRX are examined. The information summarized in this review should provide insights into contriving novel approaches for the treatment of cataract.