Improving FIB-SEM Reconstructions by Using Epoxy Resin Embedding

Abstract

Segmentation of FIB-SEM data remains a major challenge to achieving accurate reconstructions. Epoxy embedding is used in this article to eliminate background data from SEM images in order to aid in segmentation and generate 3D reconstructions of conventional high surface area CLs from FIB-SEM images. Two CL samples with the same composition but different hours of operation, namely, beginning of life (BOL), i.e. post conditioning, and end of life (EOL), i.e., post failure, were used. The samples were imaged with and without epoxy embedding to characterize the difference in the structure of the sample due to sample preparation. Further, the use of two CL samples allowed the quantification of the differences in the structure of the CL due to degradation and ensure validity of the sample preparation across multiple CL samples. Image analysis showed that a simple thresholding algorithm, such as Otsu, was sufficient to accurately segment the images for the sample with epoxy embedding due to the lack of background features. Statistical descriptors, such as porosity, two-point correlation function, chord length function, specific interface area and pore size distribution, and effective diffusion coefficient are used to quantify the differences in the reconstructed structures of the CLs with different sample preparation. Results showed that the CL reconstructions of the epoxy embedded samples had a higher porosity, larger pore sizes and lower specific interface area due to the more accurate segmentation and removal of background features.