Synthesis and characterization of $BiFeO_3$ with various nanostructures for lead-free piezoelectric energy harvesting applications

Abstract

The demand for portable electronic devices and wireless sensor networks is growing increasingly with advancing in wireless and micromechanical system technology. As these kinds of devices are portable, it needs an external power source. In most cases this power source is the conventional batteries. However, batteries are a significant source of size, weight and inconvenience to present-day portable, hand held and wearable system. Consequently, alternatives to conventional batteries for portable electronics and wireless sensor networks have been considered recently. One fascinating alternative is to use the ambient energy such as vibration, wind, solar thermal, solar light, and geothermal energy. Harvesting such energy may directly power electronic devices and wireless sensor networks if the energy source is constant and predictable. Among the various ambient energy sources, piezoelectric energy harvesting is promising because it can generate sufficient energy for many applications with low to medium power requirements. In the piezoelectric energy harvesting applications, the harvested energy per unit volume is proportional to piezoelectric constant and piezoelectric voltage constant. As piezoelectric voltage constant is inversely proportional to dielectric constant, materials with high piezoelectric constant and low dielectric constant are advantageous for piezoelectric energy harvesting applications. Perovskite $BiFeO_3$ (BFO), which shows ferroelectric, antiferromagnetic, and ferroelastic properties at room temperature, has high ($\It{T_N}$=640 K, and $\It{T_C}$=1100 K) phase transition temperatures making it very attractive not only for the fundamental physics but also from application point of view. As for BFO ceramics and thin films, although the reported piezoelectric coefficients are relatively low, the dielectric constants were also very low (40 - 100), Consequently, BFO ceramics and thin films might be good candidate material for lead-free piezoelec...