טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAbu Yossi
SubjectMicro Mechanics of Domain Switching in BaTiO3
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Doron Shilo
Full Thesis textFull thesis text - English Version


Abstract

Domain polarization switching significantly influences the physical properties of ferroelectric materials as well as their electromechanical response. Hence, the ability to measure and simulate the kinetics of domain switching is essential for the implementation of ferroelectric materials in new applications, such as micro-actuators and non-volatile data storage elements. A key property for domain switching modeling is the kinetic relationships of individual domains, i.e. the velocity in which an individual domain grows as a function of the electromechanical driving force. Despite its importance, the kinetic relationships of 90o polarization switching, which determines the electromechanical response of ferroelectrics, has barely been studied since its measurement requires both high spatial and temporal resolution. This dissertation describes the development of an experimental method for studying the kinetic relationships of 90o domain switching in single ferroelectric crystals such as BaTiO3 and PbTiO3. For this purpose, a high-voltage electric pulser was developed, which allows the application of rectangular pulses with amplitude of up to 10 kV and a rise/fall time of 50 ns. The growth of individual domains is tracked by observing the samples under an optical microscope before and after the pulse application. Experimental observations exhibit several micro-mechanical phenomena such as the nucleation of new domains with a needle shape and non-uniform domain switching which results in strain incompatibility and cracking. In addition, the velocity of sidewise domain growth was measured under several different amplitudes of the electric field.