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In most research, Oswald ripening and/or oriented aggregation processes are used to describe the Ceria (CeO2) nano particles crystals growth mechanism pathway. However, these analysis on the crystals structures and morphologies are done after the hydrothermal reaction, making it challenging to assign the growth pathways of the nano crystals. In this work, we studied the detailed in-situ structural analysis on the growth mechanisms pathways of hydrothermal synthesized CeO2 nanocrystals through the use of electron tomography. Based on the findings, oriented aggregation process plays the primarily role as the mechanism for CeO2 nanocrystals growth in hydrothermal reactions, while Oswald ripening process plays a secondary role in hydrothermal reactions. The study provides a representative pathway for the initial nucleation and growth of CeO2 for hydrothermal process in different synthesis conditions.

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Spectroscopic ellipsometry (SE) and synchrotron x-ray scattering have been applied to the non-destructive characterization of biaxial tensile strained silicon (ξ-Si). SE data from 250nm - 500nm were acquired from three epitaxial ξ-Si samples grown on silicon germanium (SiGe) virtual substrates by chemical vapor deposition (CVD). The SE data was fitted by a two-step procedure using a parametric dielectric function model for crystalline semiconductors and structural data obtained separately from X-ray scattering. By monitoring the shift of the E1 critical point in the fitted dielectric function spectrum, the tensile strain of ξ-Si can be determined from known elastic constants and deformation potentials of Si. Strain values obtained are generally in agreement with Raman measurements. The structural characteristic of the sample with the highest germanium concentration in the virtual substrate was further studied by reciprocal space mapping (RSM) and atomic force microscopy.