book of abstracts - IM2NP

A B S T R A C T S MONDAY, JUNE 28 N A N O S E A 2 0 1 0
18H10-18H30
Self-organized Ce1-xGdxO2-y Nanowire Networks with Ultrafast
Coarsening resulting from Anisotropic Strain.
M. Gibert, P. Abellán, F. Sandiumenge, T. Puig, X. Obradors (Institut de Ciència de
Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, Catalonia, Spain) mgibert@icmab.es
1 – Introduction
Assembling arrays of ordered nanowires is a key objective for many of their potential applications. However,
a lack of understanding and control of the nanowires‟ growth mechanisms limits their thorough development.
In this work, we report a new path towards self-organized epitaxial nanowires networks produced by high
throughput solution methods.
2 – Abstract
Fine control of interfacial energy through growth conditions enables us to select the crystallographic
orientation of Ce1-xGdxO2-y (CGO) nanostructures on perovskite substrates (i.e., LaAlO3 (LAO)),
providing us with a powerful tool to study the formation of islands with different degree of lateral aspect
ratio c. Self-organized and stable uniform square-based nanopyramids form when the crystallographic
orientation (001)CGO[110]||(001)LAO[100] is promoted [1]. In contrast, anisotropically strained CGO
nanowires are generated when the (011) orientation is grown on the (001) surface of the LAO single-crystals.
As a result, self-organized anisotropic nanostructures with aspect ratios above ~100 oriented along two
mutually orthogonal axes are obtained leading to labyrinthine networks. Detailed experimental analyses and
thermodynamic modeling has enabled us to identify two requisites to generate such epitaxial nanowires; a
thermodynamic driving force for an unrestricted elongated equilibrium island shape, and an ultrafast
effective growth rate. Ultrafast coarsening (~60 nm min-1) derives from Ostwald ripening and anisotropic
dynamic coalescence, both promoted by strain-driven attractive nanowire interaction, and from fast
recrystallization enabled by rapid atomic diffusion associated to a high concentration of oxygen vacancies.
3 – Conclusion
Hence, we propose a new and high throughput approach to generate self-organized nanowire templates,
which has a wide potential for many materials and functionalities. The thermodynamic origin and the kinetic
mechanisms enabling their formation are fully scrutinized.
[1] Gibert, M. et al., Adv.Materials 19, 3937 (2007).
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