| Combining a pyroelectric ceramic and a polymer matrix to form a flexible composite with coupling properties in between that of two individual phases has received much attention. In this paper, bismuth trichloride is been added into the PVDF film to improve the film`sβ-phase content, and the mechanism of bismuth trichloride in the film is been discussed initially though the film`s micro-structure;The specimens of PMNSZT/PVDF composites are prepared by traditional solvent casting method, and an appropriate amount of bismuth trichloride is been added into the composites to improve the overall performance of materials; the pyroelectric ceramic volume fraction, the content of bismuth trichloride which impact dielectric, piezoelectric and pyroelectric properties of the pyroelectric composite has been studied systematically. The main research is listed as follow:The PVDF thick films are prepared by solvent casting, bismuth trichloride is been added in the PVDF film to improve the film`sβ-phase content. The results of PVDF thick films` XRD and FT-IR micro-analysis show that: after added BiCl3, the crystal form of PVDF thick films changed, and formed a new phase. When the addition of BiCl3 is 2%, theβ-phase content in the films is the highest; And when 4% and 6%,β-phase content becomes lowly, this may be due to excessive BiCl3 molecules which pass through the fluoride bridge attached to the PVDF main chain, which affecting the crystallization of PVDF.The specimens of PMNSZT/PVDF pyroelectric composites are prepared by traditional solvent casting method, and an appropriate amount of bismuth trichloride is been added into the composites to improve the overall performance of materials; The surface morphology and microstructure are discussed through SEM, XRD. The affects of the ceramic volume, the addition of BiCl3 on the pyro, piezo and dielectric properties are discussed. The results show that when the ceramic volume reaches to 0.4, the composite material shows the best overall performance: the piezoelectric coefficient d33=6PC/N, dielectric loss tanδ=0.02, relative dielectric constantεr=22.6, pyroelectric coefficient p= 4.6×10-8C/cm2·K, the detectivity figures of merit Fd =9.24×10-5Pa-1/2. When the addition of BiCl3 is 2%, the composite material reached the best overall performance, the piezoelectric coefficient d33=7PC/N, tanδ=0.0196,εr=22.64, pyroelectric coefficient p and the detectivity figures of merit Fd are up to a maximum of 5.2×10-8C/cm2·K, 10.5×10-5Pa-1/2, compared with the composite which did not add BiCl3, Fd increased 13.6%. |
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