For more than 50 years, lead zirconate titanate (PZT) and related lead-based perovskite compositions have been the mainstay for a wide range of piezoelectric applications, such as actuators, sensors, and ultrasound transducers, owing to their superior piezoelectric and electromechanical properties. In the last few years, research studies have become more concentrated in the development of lead-free piezoelectric ceramics with properties comparable to those of PZT ceramics due to environmental regulations, for example, the legislation regarding lead-containing equipment will be enforced in the EU as the draft directives on Waste from Electrical and Electronic Equipment (WEEE), Restriction of Hazardous Substances (RoHS), and end-of-life vehicles (ELV). It is expected that the USA and Japan will also have similar regulations in the near future.The key material properties that are typically considered for piezoelectric applications are electromechanical coupling (k ij ), dielectric permittivity (e r ), and piezoelectric coefficients (d ij ). For example, high strain actuators, such as fuel injectors, piezoelectric materials require high strain d 33 , e.g., >600 pC/N with broad temperature usage range, being operational temperature range from À50 to 150 C [41]. For medical ultrasound transducers, the figure of merit is electromechanical coupling factor, since high coupling factor allows effective energy conversion in both transmitting and receiving energy, improving bandwidth and sensitivity of the transducer response. The dielectric permittivity (e r ) of a piezoelectric material is an important consideration for the design of transducer since it determines the electrical impedance of the transducer. High permittivity is also beneficial for achieving high piezoelectric response of piezoelectric materials since e r is correlated to a piezoelectric constant (d ij )