Effect of Domain Wall Motion and Phase Transformations on Nonlinear HystereticConstitutive Behavior in Ferroelectric Materials

Ferroelectric;Ferroelastic;Single crystal;Continuous phase transformation;Micromechanical model

Webber, Kyle Grant ; Mechanical Engineering

University:Georgia Institute of Technology

Department:Mechanical Engineering

关键词: Ferroelectric;    Ferroelastic;    Single crystal;    Continuous phase transformation;    Micromechanical model;   

Others  :  https://smartech.gatech.edu/bitstream/1853/22695/1/webber_kyle_g_200805_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

The primary focus of this research is to investigate the non-linear behavior ofsingle crystal and polycrystalline relaxor ferroelectric PMN-xPT and PZN-xPT throughexperimentation and modeling.Characterization of single crystal and polycrystalline specimens with similarcompositions was performed. These data give experimental insight into the differencesthat may arise in a polycrystal due to local interaction with inhomogeneities. Singlecrystal specimens were characterized with a novel experimental technique that reducedclamping effects at the boundary and gave repeatable results. The measuredexperimental data was used in conjunction with electromechanical characterizations ofother compositions of single crystal specimens with the same crystallographic orientationto study the compositional effects on material properties and phase transition behavior.Experimental characterization provided the basis for the development of a modelof the continuous phase transformation behavior seen in PMN-xPT single crystals. In themodeling it is assumed that a spatial chemical and structural heterogeneity is primarilyresponsible for the gradual phase transformation behavior observed in relaxorferroelectric materials. The results are used to simulate the effects of combined electricaland mechanical loading.An improved rate-independent micromechanical constitutive model based on theexperimental observations of single crystal and polycrystalline specimens under largefield loading is also presented. This model accounts for the non-linear evolution ofvariant volume fractions. The micromechanical model was calibrated using single crystal data. Simulations of the electromechanical behavior of polycrystalline ferroelectric materials are presented. These results illustrate the effects of non-linear single crystal behavior on the macroscopic constitutive behavior of polycrystals.