The Study Of Preparation Procedure Of Perovskite Ceramic Fibers Based On Electrospinning

In this paper,the preparation of typical perovskite strontium barium titanate fibers(Ba0.6Sr0.4TiO3 NFs,BST NFs)and barium titanate fibers(BaTiO3 NFs,BT NFs)with large aspect ratio was targeted.The sol-gel combined with electrospinning method was used,and the orthogonal test design was adopted.Barium acetate and strontium acetate were used as barium sources and strontium sources,and tetrabutyl titanate was used as titanium sources.The optimized conditions were the spinning solution ratio,solvent system,thickening agent polyvinylpyrrolidone(PVP),the distance between the tip and receiver,spinning solution flow rate,spinning voltage and calcination temperature,etc;On this basis,BST NFs/PVDF and BT NFs/PVDF composites were prepared by combining the two kinds of ceramic fibers with polyvinylidene fluoride(PVDF)polymers,respectively,to investigate the effect of fibers content on energy density of the composites.The following research results were obtained.The optimized([Ba]+[Sr])/[Ti]molar ratio was 1.07 and the optimized PVP content was 8.7 wt%.Acetic acid-N,N-dimethylformamide(DMF)-acetylacetone was used as the optimized solvent system.PVP-Ba0.6Sr0.4TiO3 composite fibers were obtained under the optimized spinning parameters,which included the distance between the tip and receiver(18 cm),the spinning solution flow rate of 1 mL/h and the spinning voltage of 19 kV.BST NFs(denoted as 3h-BST NFs)with diameter of about 200 nm and the aspect ratio of 130:1 were prepared after calcination at 900? for 3 h;The optimized[Ba]/[Ti]molar ratio was 1.07 and the optimized PVP content was 8.6 wt%.The optimized solvent system was acetic acid-DMF-acety lacetone.PVP-Ba0.6Sr0.4TiO3 composite fibers were obtained under the optimized spinning parameters,which included the distance between the tip and receiver(21 cm),the spinning solution flow rate of 0.5 mL/h and the spinning voltage of 21 kV.BT NFs(denoted as 3h-BT NFs)with diameter of about 200 nm and the aspect ratio of 125:1 were prepared after calcination at 900? for 3 h.SPSS software was used to fit the aspect ratio of BT NFs under continuously varying spinning parameters.The results showed that the maximum aspect ratio 135:1 was similar to the experimental result 125:1,which indicated that the experimental data were reasonable.This paper analyzed the dependence between the morphology of the fibers and the solvent system.It was found that acetylacetone acted as catalyst to make the fibers longer;acetic acid balanced and stabilized the hydrolysis-polymerization process to improve the surface morphology of the fibers;DMF increased the viscosity and surface tension of the spinning solution,and decreased the fibers diameter;the ethanol was volatile,causing fibers diameter to increase and crack on the surface.The effect of 3h-BST NFs addition on the energy density of BST NFs/PVDF composite was studied.It was found that when the amount of 3h-BST NFs was 1 vol%,the dielectric constant was 11.71,the maximum breakdown strength was 345.5 kV/mm,and the energy density reached to 6.18J/cm3,which was 1.67 times that of porous spherical BST NPs/PVDF composites.This paper compared the energy density of composites obtained by adding 1 vol%3h-BT NFs and spherical BaTiO3.The results showed that the energy density of 3h-BT NFs/PVDF composites was 6.01 J/cm3,which was 1.57 times that of BT NPs/PVDF composites.The increase of energy density can be attributed to the addition of fibers with large aspect ratio,which enhances the polarization strength of the internal interface of the composite.