Orientation symmetry breaking in self-assembled Ce_1−xGd_xO_2−ynanowires derived from chemical solutions

Abstract

A novel approach to perform an independent study of the nucleation and coarsening of Ce0.9Gd0.1O2−ynanowires is presented.

Unveiling the Nucleation and Coarsening Mechanisms of Solution-Derived Self-Assembled Epitaxial Ce0.9Gd0.1O2–y Nanostructures

“…CGO NDs grown on (001)YSZ substrates have a larger strain configuration than those grown on (001)LAO ( (001)CGO||(001)YSZ~ -5% vs (001)CGO||(001)LAO~ -1%) 48 . Large values of strain will contribute increasing the nucleation barrier for a given supersaturation as reported before 44,63 . Therefore, the energy required to overcome the nucleation barrier and for the stabilization of nuclei will be higher which means that higher temperatures are needed.…”

“…It also seems to be the same case for closed CSD systems where atoms are already deposited on the substrate surface prior to the formation of nanostructures ( Figure S3). theoretical studies where we have demonstrated that coarsening of NWs along their length is thermodynamically driven by the continuous reduction of the system's energy 63 . Therefore, NWs' elongation seems to be a kinetically-driven thermodynamic process.…”

“…Instead, the length b experiences a fast increase in size from 40 to 90 nm which suggests a stronger contribution of the length to the rise in volume, also confirmed by calculating the lateral aspect ratio c ( Figure S6d). We have demonstrated before that the growth of NWs is thermodynamically promoted along their length 48,57,63,80 . The non-linear growth of the volume can be related to a variation of the nucleation rate with temperature as we will see later.…”

“…The most common form of CGO nuclei, as we will see later, is a trapezoidal-prismatic shape (Figure 1) with a height h, width a and length b, and the lateral facets associated with the width and length are tilted at angles δ and θ, respectively. Then, the variation of the Gibbs free energy can be written as a function of the effective diameter S (= √ · ) 44,58,63,80 :…”

“…Parameter values for the different systems are reported in the literature and can be also found in the Supporting Information (Table S1) 59,[80][81][82] . Then, the nucleation barrier as a function of the supersaturation can be written as 48,58,63,80…”