Education

Research Description

Dr. Nina Balke is an Associate Professor in the Materials Science and Engineering Department and the Director of the Analytical Instrumentation Facility. She received her MS and Ph.D. in Materials Sciences from the Technical University of Darmstadt in Germany. Dr. Balke’s research focuses on utilizing state-of-the-art atomic force microscopy to understand and discover new nanoscale materials functionality driven by electric fields and potentials for information and energy technology. This encompasses electromechanical, mechanical, and transport phenomena in inorganic materials and across fluid-solid interfaces. She received her Ph.D. in Materials Sciences from the Technical University of Darmstadt, Germany, in 2006. After being a Feodor-Lynen Fellow of the Alexander von Humboldt Foundation at the University of California in Berkeley, she became a research staff member at the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory in 2010 before she joined NCSU in 2021.

Publications

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Grants

Through Thickness Variations of Degradation Phenomena in Piezoelectric and Ferroelectric Ceramics, CDP Core Project

NCSU Center for Dielectrics and Piezoelectrics (CDP)(7/01/22 - 6/30/23)

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Through Thickness Variations of Degradation Phenomena in Piezoelectric and Ferroelectric Ceramics, CDP Core Project

Sponsor: NCSU Center for Dielectrics and Piezoelectrics (CDP)

Start Date: 7/01/22

End Date: 6/30/23

Abstract

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.

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