Maoyan Fan

Significant influence of film thickness on the percolation threshold of multiwall carbon nanotube/low density polyethylene composite films

A series of multiwall carbon nanotube/low density polyethylene composite films with different thicknesses and different carbon nanotube volume fractions was prepared and studied. The result showed an interesting phenomenon which has not been reported before: when the thickness was reduced to the length range of the carbon nanotube filler, it could remarkably affect the percolation threshold of the composite films. Classical theories have been introduced to describe the phenomenon. This result could have significance in future applications of percolative composite thin/thick films.

Enhanced antiferroelectric and electric-induced pyroelectric properties of Mn-substitued (Pb0.832Ba0.138La0.02)(Zr0.7Ti0.05Sn0.25)O3 ceramics

(Pb0.832Ba0.138La0.02)(Zr0.7Ti0.05Sn0.25)O3 ceramics with stable antiferroelectric phase at room temperature were fabricated by Mn doping. The enhancement of antiferroelectric phase is attributed that the substitution of Mn ion into the B site decreased tolerance factor of the ceramics. The largest pyroelectric figure of merit of 25 × 10−5 Pa−0.5 was obtained in (Pb0.832Ba0.138La0.02)(Zr0.7Ti0.05Sn0.25)O3 antiferroelectric ceramics with 0.2 mol. % Mn doping, which is far higher than that of convention phase transition materials. The increase of the pyroelectric response was attributed to the improvement in dc field-induced dielectric enhancement effect and the reduction in dielectric loss.

Large electric-induced pyroelectric properties in (Pb0.87La0.02Ba0.1) (Zr0.7Sn0.24Ti0.06)O3 antiferroelectric ceramics with excess PbO

(Pb0.87La0.02Ba0.1) (Zr0.7Sn0.24Ti0.06)O3 (PLBZST) antiferroelectric ceramics with the addition of 0–9 wt. % excess PbO were fabricated by the conventional solid-state reaction process, and their microstructure, dielectric, and pyroelectric properties were systemically investigated. When excess PbO content was less than 9 wt. %, two pyrochlore phases were formed along with the perovskite phase. Compared with common specimens, PLBZST antiferroelectric ceramics with excess PbO exhibited a higher pyroelectric coefficient and a lower dielectric loss, which are beneficial for the development of pyroelectric devices. Around the Curie temperature, as the excess PbO increased from 0 wt. % to 9 wt. %, PLBZST ceramics’ pyroelectric coefficient increased from 1600 μC/m2K to 4000 μC/m2K, and the figure of merit increased from 40 × 10−5 Pa−0.5 to 140 × 10−5 Pa−0.5 under a 400 V/mm dc field. The largest figure of merit of 200 × 10−5 Pa−0.5, which is about 8 times higher than that of conventional phase transition materi...