(Keynote) Emergent Effects of Global Surfaces on Local Microstructure Designs for Functionality in Heterogeneous Functional Materials

Abstract

Heterogeneous functional materials are of special importance to the design of functional devices such as fuel cells, batteries, and capacitors, but they are also critical to applications like energy storage and the confinement of nuclear waste materials. Morphology design is critical to all of these (and other) applications, and much literature records the science and engineering of that subject. But the rules we generate and recite that control particle / void space and shape, surface to volume / phase shape selections, constituent distributions and other aspects of those microstructure designs do not predict the emergent properties and functionalities of such materials when a global surface influences or controls the basic transport or diffusion of active species into and out of those microstructures when they act as functional materials. Examples of such emergent properties and functionalities will be identified and discussed in the present paper, with the intent of identifying general concepts and principles that help us to design successful microstructures in those situations. Subjects of the discussion will include threshold volume fractions, short vs. long term response, surface to volume ratios, interface / interphase effects, and critical path concepts. Examples will be provided from several application fields, and some directions will be suggested.