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Ceramic-polymer pyroelectric composite materials with favorable flexibility hold great potential for wearable sensors and energy harvesters, and the further improvement in pyroelectric properties would push them closer to practical application. In this work, an uniaxial stretching method was proposed to optimize the performance of lead zirconate titanate nanowires (PZT NWs)/polyvinylidene fluoride (PVDF) 1–3 composites. With just one stretching treatment, the pyroelectric coefficient of the composite was enhanced by inducing more β phase in PVDF matrix, and the permittivity was decreased by reorientation of PZT NWs to the strain direction in the meantime. As a result of the incorporated effects, the figure of merit of the stretched composite with orientated PZT NWs increases to the value of 2.18 × 10−10 C cm−2 K−1, which is 619% higher than that of untreated samples at 35 °C. This work could provide an efficient approach to fabricate high-performance ceramic-polymer pyroelectric composite materials. [ABSTRACT FROM AUTHOR]

Antiferroelectric ceramic/polymer composites can be used as a base material in the future application of the tunable photonic crystals even high strain actuators, shock-activated energy transducer and high-density capacitor for their easy fabrication, good flexibility, precise control of the process parameters and good dielectric tenability affected by electric field. The adjustable dielectric effect in the antiferroelectric ceramic/polymer composites are experimentally studied with specific interest in the dependence on the inducing electric field up to 100 V/mm. The particulate composite consisting 20 vol% of polystyrene (PS), 80 vol% of lead barium lanthanum zirconium tin titanate (PBLZST) is fabricated by the means of solution mixing and hot pressing in lab. Scanning electron microscopy was used to investigate the morphology of the composites and the particle distribution, which shows that the nano carbon powders evenly dispersed in composite materials. It is observed that the addition of coupling agent and nano carbon powders influence the dielectric properties, such as the value of the tunability rate of dielectric permittivity and loss tangent. This is partly attributed to coupling agent improve two phase separation and enhanced the effect of ceramic phase in composites, and partly attributed to carbon powders which create electric paths between PBLZST Particles in composite material, which together make more electric field applied to ceramic phase and influence the response of dielectric permittivity controlled by electric field. As a result, the best electric field value to adjust the dielectric permittivity (ε) is 100 V/mm and maximum tunability rate was 49 %, with coupling agent at 10 wt% and nano carbon powders at 1 wt% in composites. [ABSTRACT FROM AUTHOR]

Transparent conductive material is used in a wide range of applications and is particularly interesting. In the present work, a series of multiwall carbon nanotubes/low density polyethylene nanocomposites with different carbon nanotubes were prepared via solution casting method. The optical transparency, morphology, and resistivity of transparent conductive films have been characterized by using UV-Vis Spectrophotometer, Field emission scanning electron microscope and Multimeter, respectively. Their electrically conductive and optically transparent properties were studied and compared. The result showed that thinner and longer multiwall carbon nanotubes were more suitable for the fabrication of flexible transparent conductive nanocomposites. The sample filled with 1 wt% of T.1 (outside diameter <8 nm, length 10-30 μm) had good transparent conductive properties (volume conductivity of 3.12 × 10 S m and optical transmittance of 62.8 % at the light wavelength of 600 nm). The high volume conductivity and optical transparency demonstrated that such kind of nanocomposite films had favorable potential in the applications from electromagnetic interference shielding to transparent electrodes. [ABSTRACT FROM AUTHOR]

The β-phase of poly(vinylidene fluoride) (PVDF) is of great technical importance because of its high dielectric constant and piezoelectric effect. In this work, we exfoliated and dispersed natural graphite to prepare 2D-graphite nanosheets (GNS) and prepared PVDF/GNS nanocomposites with different GNS volumes from 1 to 7 ml as film via solution casting method. The concentration of the supernatant was about 0.3 mg/mL. The effect of GNS on the β-phase formation and mechanisms of piezoelectric formation in the PVDF/GNS nanocomposites were investigated. The results showed that with the varying amounts of GNS, the crystalline structure, the morphology, and the dielectric and piezoelectric properties of PVDF/GNS nanocomposites changed. GNS acts as an effective nucleation agent with the orientation almost parallel to the surface of the film meanwhile increasing the amount of beta phase in the PVDF matrix with increasing amount of GNS, also the relative dielectric constant and dielectric loss of the nanocomposites increased with increasing amount of GNS. The value d also increased with increasing amount of GNS, and reached a maximum (6.7 pC/N) with 6 ml GNS. The mechanism of piezoelectric formation was proposed based on experiment results of PVDF/GNS nanocomposites. [ABSTRACT FROM AUTHOR]

(PbLaBa)(ZrSnTi)O (PLBZST, 0.06≤ x≤0.09) antiferroelectric ceramics were fabricated by conventional solid state reaction process, and their ferroelectric, dielectric, and pyroelectric properties were systemically investigated. PLBZST with different Ti content were all confirmed to be in an antiferroelectric phase at T=50°C, which is close to the lowest phase transition temperature. Compared with conventional FE ceramics, PLBZST antiferroelectric ceramics exhibited higher electric field induced pyroelectric coefficient ( p). As the content of Ti increased from 0.06 to 0.09, the pyroelectric coefficient increased from 1000 to 6500 μC/mK under a 500 V/mm DC bias field. The maximum pyroelectric coefficient of 8400 μC/mK was obtained at x=0.09 when an 850 V/mm DC bias field was applied, which is far larger than that of conventional phase transition pyroelectric materials. Large pyroelectric response is beneficial for the development of infrared detectors and thermal imaging sensors. [ABSTRACT FROM AUTHOR]