Piezoelectric materials are capable of converting mechanical energy into electrical energy and vice versa. These materials have been at the forefront of technological innovations ever since their emergence in the late 19th century. Piezoelectrics have found their niche in communication, automobile, aerospace, and several other industries relying on electromechanical systems. The excellent piezoelectric properties of materials like lead zirconium titanate (PZT) have made them a popular candidate in the production of actuators, sensors, and transducers. However, PZT was classified as a hazardous material in 2003 by the European Union due to the toxic nature of its lead oxide precursor. Efforts have been made by the scientific community to shift to more environmentally friendly, lead-free, piezoelectric systems. Bismuth, sodium, and potassium have garnered much attention as substitutes for lead due to their non-toxic nature. Piezoceramics such as barium titanate (BT), bismuth ferrite (BFO), potassium sodium niobate (KNN), and potassium sodium lithium niobate (KNLN) have become increasingly popular.

Bismuth ferrite’s (BFOs) high piezoelectric Curie temperature (825 °C) coupled with its lead-free nature makes it one of the more interesting PZT alternatives. However, the synthesis of phase pure BFO is difficult due to the presence of parasitic iron and bismuth-rich secondary phases. The electrical conductivity of BFO, which is considerably higher than that of PZT, is also an issue. The presence of a high electrical leakage current is generally attributed to the defects and oxygen vacancies in bismuth ferrite. Through doping, it is possible to control the density of these free moving charges and oxygen vacancies. In this thesis, we use the method of solid-state reaction synthesis with subsequent sintering for the preparation of doped BFO samples. This work aims to develop highly polarizable doped BFO systems with low leakage characteristics which could potentially be utilized for high-temperature sensing applications.

An enhancement in polarization was observed by doping BFO with trace amounts of cobalt. The incorporation of titanium into BFO led to the reduction of conductivity and caused an improvement in the leakage characteristics. A co-doped system of cobalt and titanium was further explored to combine the positive characteristics of both individual dopants. The result was a highly polarizable system (0.25-0.25 at% Co-Ti) with low conductivity and excellent leakage characteristics. A solid solution system of BFO with strontium titanate (STO) was also explored. The 30 at% STO system showed extremely large values of piezoelectric charge constant. The thesis was concluded by performing some high-temperature measurements on the 0.25-0.25 at% Co-Ti and 30 at% STO systems.