The overarching goal of this proposal is to determine the local effects of degradation throughout the thickness of piezo- and ferroelectric ceramics. This will be enabled using 3D analysis of the microstructure using advanced focused ion beam and tomography methods as well as Atomic Force Microscopy (AFM) techniques. The use of AFM has been successfully applied by co-PI Balke to reveal the local effects of bipolar fatigue in polished cross-section PZT ceramics [1]. In combination, this multi-modal approach covers many relevant length scales and will generate comprehensive insights into the mechanical and functional degradation throughout the thickness of bulk ceramics and will be applied to time and field-driven degradation relevant to actuator applications, such as aging and unipolar fatigue. This will allow to directly identify areas which are most affected by degradation, such as electrode-near regions, and identify their consequences on local and global piezoelectric and ferroelectric properties. Specifically, we will use (1) plasma Focused Ion Beam (pFIB) to rapidly characterize large blocks of fatigued regions both near the surface and in the bulk, (2) X-ray Nano-computed tomography (nano-CT) to identify the presence and location of internal microcracks, and (3) Piezoresponse Force Microscopy (PFM) to characterize the change in local domain structure, domain wall mobility, as well as qualitative changes in dielectric constant throughout the sample thickness. All local observables will be directly compared to macroscopically measured effects of degradation, such as strain and polarization to bridge the information obtained on different length scales and to explore the origin of degradation in the context of unifying degradation laws. This information will allow to establish the role of the microstructure and electrode/ceramic interface on reliability and lifetime predictions.

The critical role of catalysts in supporting advanced industries and technologies cannot be overstated. From nitrogen fixation to petroleum cracking, even a moderate improvement in catalyst efficiency can result in monumental energy and monetary savings. As the state of the art develops, so does the complexity of these catalysts and their manufacturing processes. Although nanoparticle catalysts are still prevalent, nanoparticle or single atom catalysts bound to non-catalytic material to modify their properties has become the topic of much research. These have often taken the form of platinum affixed to substrates such as ceria or alumina. However, the introduction of a support structure, and a corresponding interface, increases the complex nature of the manufacturing environment. Therefore, to control the resulting catalyst morphology and active sites, it is necessary to understand the reaction pathways that connect the chemical precursor to the final product and determine how the introduction of a compatible substrate affects catalyst nucleation and growth. Historically, efforts to research catalytic reaction paths have been performed on large sample volumes using various in situ diffraction and spectroscopic techniques. In this manner, it is possible to generally determine what phases and oxidation states are involved in the process. However, such techniques are not ideal for delving into the highly localized and non-uniform reactions that occur in the angstrom scale environment of nanoparticle nucleation and growth at an interface. For this reason, alternate techniques based on transmission electron microscopy (TEM) have been employed successfully to observe nanoparticle synthesis at atomic resolution in a variety of operant environments. However, to date, few TEM studies have successfully imaged the intermediate steps required to reduce a catalyst������������������s chemical precursor into a metallic state and thereby understand its nucleation and growth processes. In large part, this has been a consequence of the commonly used liquid phase in situ environment that renders solute chemical imaging impossible. Here we proposed to use atomic resolution, in situ TEM to study the effect of environmental variables in the manufacturing of catalytic nanoparticles from a solid state precursor. The chief system of interest will be that of platinum������������������s chemical precursors with a range of inert substrates. Initial steps toward the accomplishment of this goal have already been taken to great success. By using a combination of low dose HAADF and iDPC, it has been revealed that initial nucleation of platinum metal from potassium tetrachloroplatinate can occur from a disproportionation reaction. This has demonstrated that the concept is technologically sound and may be reproduced on more complex systems to gauge the effect of substrate-rich environments. o overcome this impediment, machine learning based compressive sensing will be developed to reconstruct the images from a limited signal. In this manner, the time resolution of the image series will be substantially improved without sacrificing interpretability.