Abstract
• BiFeO 3 particles were embedded in non-conducting non-piezoactive PVDF terpolymer. • Dielectric and piezoelectric properties of BiFeO 3 -PVDF composite with different volume fraction were studied. • The piezoelectric charge and voltage coefficients of granular BiFeO 3 were determined by using Yamada and Poon model. BiFeO 3 is an interesting multiferroic material with potential use in sensors and transducers. However, the high coercive field and low dielectric strength of this material make the poling process extremely difficult. Poling becomes a lot easier if the ceramic particles are incorporated in a non-conductive polymer with comparable dielectric properties. In this work, unstructured composites consisting of BiFeO 3 particles in a non-piezoactive PVDF terpolymer matrix are made with a ceramic volume fraction ranging from 20% to 60%. The highest piezoelectric charge and voltage constant values (d 33 = 31 pC/N and g 33 = 47 mV m/N) are obtained for a BiFeO 3 -PVDF terpolymer composite with a volume fraction of 60%. The Poon model is chosen to analyse the volume fraction dependence of the dielectric constant while the modified Yamada model is used to analyse the piezoelectric charge constant data. It is concluded that the maximum possible piezoelectric constant for bulk BiFeO 3 can be as high as 56 pC/N.
Highlights
BiFeO3, called Bismuth Ferrite or BFO, like many piezoelectrics, crystallises with a distorted rhombohedral perovskite-type structure and was first discovered in the late 1950s by Royen and Swars [1]
Samples of pure polymer and BiFeO3 ceramics were prepared to determine the dielectric constants of the polymer and BiFeO3
PVDF terpolymer films with a thickness of around 200 μm were prepared by the same method as for the composites
Summary
BiFeO3, called Bismuth Ferrite or BFO, like many piezoelectrics, crystallises with a distorted rhombohedral perovskite-type structure and was first discovered in the late 1950s by Royen and Swars [1]. Interest in this material only rose in the early 2000s due to the high Curie temperature (~825 °C [2]) and the high spontaneous polarization: 50–60 μC/cm in thin films [3], ~100 μC/cm in single crystals along the [111]pc direction [4] and 45 μC/cm in bulk ceramics [5]. Due to the high coercive field required to pole BiFeO3, it is important to increase its insulating properties to reduce the leakage currents [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
