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Full-Text Articles in Engineering
Field-Limited Migration Of Li-Ions In Li-Ion Battery, Fuqian Yang
Field-Limited Migration Of Li-Ions In Li-Ion Battery, Fuqian Yang
Chemical and Materials Engineering Faculty Publications
The migration of Li-ions in lithium-ion battery cannot be simply described by Fick's second law; the interactions among ionic migration, field, and stress need to be taken into account when analyzing the migration of Li-ions. Using the theory of thermal activation process, the flux for ionic migration under concurrent action of electric field and mechanical stress is found to be a nonlinear function of the gradient of electric potential and the gradient of stress. Electric field can either accelerate or retard the growth of the lithiation layer, depending on polarity of the field.
Thermotropic Phase Boundaries In Classic Ferroelectrics, Tom T. A. Lummen, Yijia Gu, Jianjun Wang
Thermotropic Phase Boundaries In Classic Ferroelectrics, Tom T. A. Lummen, Yijia Gu, Jianjun Wang
Materials Science and Engineering Faculty Research & Creative Works
High-performance piezoelectrics are lead-based solid solutions that exhibit a so-called morphotropic phase boundary, which separates two competing phases as a function of chemical composition; as a consequence, an intermediate low-symmetry phase with a strong piezoelectric effect arises. In search for environmentally sustainable lead-free alternatives that exhibit analogous characteristics, we use a network of competing domains to create similar conditions across thermal inter-ferroelectric transitions in simple, lead-free ferroelectrics such as BaTiO3 and KNbO3. Here we report the experimental observation of thermotropic phase boundaries in these classic ferroelectrics, through direct imaging of low-symmetry intermediate phases that exhibit large enhancements …