Effect on dielectric properties of LDPE due to addition of different structure of BiFeO3powders

摘要

Lamellar and spherical BiFeO_3 powders were synthesized by the hydrothermal route. The morphology feature of BiFeO_3 powders was shown using scanning electron microscope. The SEM images of the lamellar BiFeO_3 powders shows the lamellar size was 1-2 μm and thickness was about 100 nm. Each crystal structure were formed of multilayer aggregate. The images of the spherical BiFeO_3 powders shows uniform feature with approximately 2 μm in size. Dielectric BiFeO_3 /LDPE composite with doping lamellar and spherical BiFeO_3 powders of different percentages including 0.2, 0.5, 1 and 2 wt%, have been successfully prepared by melt blending route. In this work, we studies AC breakdown strength and dielectric spectrum of BiFeO_3 /LDPE composite. The AC breakdown strength of LDPE was increased due to addition of lamellar and spherical BiFeO_3 powders of 0.2, 0.5, 1 and 2 wt%. The AC breakdown strength of BiFeO_3 /LDPE firstly increased and then decreased with the increasing of BiFeO_3 content. The AC breakdown strength of lamellar-BiFeO_3 /LDPE composite is higher than of spherical-BiFeO_3 /LDPE. The dielectric property of BiFeO_3 /LDPE composite was investigated. The relative permittivity of BiFeO_3 /LDPE composite is greater than LDPE and firstly decreased then increased with the increasing of doping BiFeO_3 content. The relative permittivity of lamellar-BiFeO_3 /LDPE composite is smaller than the spherica-BiFeO_3 /LDPE composite under the same conditions.