Three-dimensional imaging of grain boundaries via quantitative fluorescence X-ray tomography analysis

Authors

Abstract

Three-dimensional visualization of material composition within multiple grains and across complex networks of grain boundaries at nanoscales can provide new insight into the structure evolution and emerging functional properties of the material for diverse applications. Using nanoscale scanning X-ray fluorescence tomography, coupled with an advanced self-absorption correction algorithm developed in this work, we analyze the three-dimensional distribution of a large number of grains and their compositions in a Ce0.8Gd0.2O2--CoFe2O4 mixed ionic-electronic conductor (MIEC) system with unprecedented accuracy and statistical significance. Our investigation reveals the formation of a new emergent phase that has not been previously reported and highly intriguing composition stability ranges for the multiple material phases within this system. Visualization of composition variation across individual grain boundaries, together with systematic composition analysis, discloses fundamental pathways of the complicated phase transformation during material synthesis with new insight for further optimizing transport property of the MIEC system.