Varistor Grain Boundary Characterization by High Resolution Analytics
Research output: Thesis › Master's Thesis
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2022.
Research output: Thesis › Master's Thesis
Harvard
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TY - THES
T1 - Varistor Grain Boundary Characterization by High Resolution Analytics
AU - Byloff, Johanna
N1 - no embargo
PY - 2022
Y1 - 2022
N2 - A novel method for the characterization of complementary parameters of single varistorgrain boundaries is proposed. The influence of grain orientation mismatch on the electricalbehaviour is discussed. Therein, electrical parameters (Current-Voltage (I-V) characteris-tic), microstructural parameters (Electron Backscatter Diffraction (EBSD) scan), and thechemical composition (Atom Probe Tomography (APT), via a Focused Ion Beam (FIB)Lift-Out) are measured. Electrical measurements of different grain boundaries are analysedand categorized according to their grain boundary misorientation. APT scans of bulk ma-terial, a parameter study as well as two complete characterizations of grain boundaries arepresented. I-V characteristics show asymmetry depending on the polarity of the interface.Concentration profiles of comprised elements are shown and an asymmetrical oxygen-zincprofile is showcased for both grain boundaries. APT measurements show heightened bismuthconcentration in the grain boundary. Cobalt only shows a peak in concentration in the grainboundary with an asymmetrical I-V characteristic, all other dopant elements show uniformbehaviour for both grain boundaries.
AB - A novel method for the characterization of complementary parameters of single varistorgrain boundaries is proposed. The influence of grain orientation mismatch on the electricalbehaviour is discussed. Therein, electrical parameters (Current-Voltage (I-V) characteris-tic), microstructural parameters (Electron Backscatter Diffraction (EBSD) scan), and thechemical composition (Atom Probe Tomography (APT), via a Focused Ion Beam (FIB)Lift-Out) are measured. Electrical measurements of different grain boundaries are analysedand categorized according to their grain boundary misorientation. APT scans of bulk ma-terial, a parameter study as well as two complete characterizations of grain boundaries arepresented. I-V characteristics show asymmetry depending on the polarity of the interface.Concentration profiles of comprised elements are shown and an asymmetrical oxygen-zincprofile is showcased for both grain boundaries. APT measurements show heightened bismuthconcentration in the grain boundary. Cobalt only shows a peak in concentration in the grainboundary with an asymmetrical I-V characteristic, all other dopant elements show uniformbehaviour for both grain boundaries.
KW - Varistor
KW - ZnO
KW - Atom Probe Tomography
KW - Grain Boundary
KW - Electrical properties
KW - Electron Backscatter Diffraction
KW - Atomsondentomographie
KW - Varistor
KW - ZnO
KW - Zinc Oxide
KW - Elektronenrückstreubeugung
KW - Korngrenze
M3 - Master's Thesis
ER -
