Effect on dielectric properties of LDPE due to addition of different structure of BiFeO₃ powders

Lamellar and spherical BiFeO₃ powders were synthesized by the hydrothermal route. The morphology feature of BiFeO₃ powders was shown using scanning electron microscope. The SEM images of the lamellar BiFeO₃ 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 BiFeO₃ powders shows uniform feature with approximately 2 μm in size. Dielectric BiFeO₃/LDPE composite with doping lamellar and spherical BiFeO₃ 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 BiFeO₃/LDPE composite. The AC breakdown strength of LDPE was increased due to addition of lamellar and spherical BiFeO3 powders of 0.2, 0.5, 1 and 2 wt%. The AC breakdown strength of BiFeO3/LDPE firstly increased and then decreased with the increasing of BiFeO3 content. The AC breakdown strength of lamellar-BiFeO₃/LDPE composite is higher than of spherical-BiFeO3/LDPE. The dielectric property of BiFeO₃/LDPE composite was investigated. The relative permittivity of BiFeO3/LDPE composite is greater than LDPE and firstly decreased then increased with the increasing of doping BiFeO3 content. The relative permittivity of lamellar-BiFeO₃/LDPE composite is smaller than the spherica-BiFeO3/LDPE composite under the same conditions.