Synthesis and studies of PVDF-BiFeO3 hybrid nano-composites for flexural piezoelectric applications

Zamin, Hasnat and Ramadurai, Ranjit (2017) Synthesis and studies of PVDF-BiFeO3 hybrid nano-composites for flexural piezoelectric applications. Masters thesis, Indian Insitute of Technology Hyderabad.

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Abstract

iv ABSTRACT. Ferroelectric ceramics such as lead zirconium titanate (PZT) and barium titanate (BaTiO 3 ) have been potentially used for solid state applications such as transducer and electromechanical devices owing to their ferroelectric and piezoelectric properties. However, fragility, inflexibility and poor processibility are inherent properties of the ceramics and hence, limi ts their application. On the other hand, polymers are flexible and easy to process which can offer a wide opportunity as flexible electronic devices. Polyvinylidene fluoride (PVDF) is a ferroelectric polymer which is extensively studied due its ferroelectr ic and piezoelectric response and is also known for its chemical and mechanical durability. Hybrid materials , such as polymer ceramic composites, have received a lot of attention in recent years. Since these materials can combine the excellent ferroelectr ic and piezoelectric properties of ceramics with the fl exibility, processing facility and strength. In this thesis, we report the synthesis and comprehensive studies of PVDF and Bismuth ferrite (BFO) composites, with 0 - 3 connectivity, which is formed when nano sized ceramic particles are homogeneously dispersed in a three - dimens ionally bound polymer matrix. Semi crystalline PVDF has three predominant phases α, β and γ with β phase associated with ferroelectric and piezoelectric properties. BFO nanoparticle s were synthesized by co - precipitation technique and PVDF - BFO thin films having thickness in micrometres , containing different weight percentages of BFO nanoparticles, were deposited by solution casting technique. Various characte rization methods, such as X - ray diffraction and Raman scattering studies were performed to determine the phase purity and structural properties of the samples. Ferroelectric and piezoelectric properties were studied using piezoresponse force microscope (PFM) analysis and Current - Vo ltage characteristic studies were carried out, to understand the polarisation current hysteresis behaviour, a typical property of ferroelectric materials. Finally, we report a detailed study done for the understanding of the origin of piezoelectric and fer roelectric phenomena in polymer, synergetic interaction of nanoparticles filler in the polymer matrix effecting the β phase formation in the PVDF aimed for flexible electronic application such as vibrational sensors and non - volatile memory devices.

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