The interesting properties of the class of ceramic materials called “ferroelectric -perovskites” have been used in wide ranging applications such as SONAR, ultrasound imaging, focusing of mirrors in space telescopes, heath monitoring of structures, automobile industry, etc. These materials produce voltage on being stressed and can change shape on application of electric-field. The latter phenomenon is known as electrostrain. The larger the electrostrain, the better the material can perform. Most piezoelectric ceramics exhibits electrostrain in the range ~ 0.2 -0.3 %. While researchers in the recent past have reported new ceramic materials with electrostrain in the range 0.4 – 0.7 %, these values are still considerably less than what can be achieved in single crystals (~ 1.3 -1.7 %). For the first time, we demonstrate that ceramic, which is very easy to make, less time and energy consuming than that required for making of a single crystal, can show electrostrain greater than 1 %. We achieved an electrostrain of 1.3 % by compositional design of the material system BiFeO3-PbTiO3-LaFeO3. The extraordinary electrostrain was possible due to ability of the ferroelectric domains to switch back to their nearly random configuration after removal of electric field. Our material design strategy can guide researchers to develop new ceramic materials with ultrahigh electrostrain. Such materials can be used as a cost-effective alternative to costly single crystals.
Bastola Narayan and Prof.Rajeev Ranjan
Reference: Narayan et. al., Nature Materials, 17, (2018) 427-431