FRG: Domain Orientation and Anisotropy in Poled Piezoelectrics

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NON-TECHNICAL DESCRIPTION Piezoelectric materials are critical for applications in sensors and actuators that enable medical ultrasound, therapies that promote bone healing, highly efficient portable power transformers, high performance diesel engines and many other applications involving conversion between electrical and mechanical energy. The goal of this research team is to improve our understanding of piezoelectrics by fully optimizing existing materials and enabling enhanced potential for industrial development of environmentally friendly, lead free piezoelectrics. The research project will also be directed towards developing educational materials on the science and engineering of piezoelectrics for students from middle school to beginning college. The educational materials will be used to enhance skill development in math and science and to foster interest in science and engineering. TECHNICAL DETAILS: Exploration of crystallographic texture with domain orientation and anisotropy in poled, lead free piezoelectrics enables understanding of the interrelationships between texture and microstructure that can lead to replacement of lead-containing piezoelectrics. This project will couple domain textures and crystallographic textures in bulk materials to understand the development of piezoelectric and other anisotropic properties. Effects of poling field, poling temperature, conductivity and intrinsic materials properties such as electrical and thermal conductivity, elasticity and thermal expansion are critical aspects for developing this understanding. The project consists of development of processing approaches to produce bulk materials that can be used to fully describe the interplay between texture and anisotropy in the rapidly evolving classes of lead free piezoelectric materials. Project investigators are considering nanoscale and microscale interactions between ferroelastic and ferroelectric domains across grain boundaries as a function of stress state, temperature and processing history via scanned surface probe techniques. The experimental aspects are pivotal to describing the relationship of texture and microstructure to properties for comparison to incisive microstructure-based numerical simulations that capture the thermodynamics and physics occurring on the scale of the domains and grains. Both the experimental and computational aspects of this project will be carried out in collaboration with colleagues in the automobile and diesel engine industries and at the Technical University of Darmstadt. This project is producing a better understanding of poling processes, the limitations imposed on poling by the underlying ferroelastic and ferroelectric domains and their interactions with grain boundaries and microstructure. Undergraduate and graduate student researchers are learning advanced techniques for numerical simulation of nanoscale and microscale effects on properties, sample preparation techniques for surface probe analysis and electron microscopy, surface probe techniques, electron microscopy and x-ray and neutron diffraction techniques.