Vapor-solid-solid growth mechanism driven by epitaxial match between solid AuZn alloy catalyst particle and ZnO nanowire at low temperature

The present paper provides a comprehensive picture of the precise mechanism of ZnO vapor-solid-solid nanowire growth at low temperatures and gives the fundamental reasons responsible [1]. We demonstrate by using a combination of synchrotron XRD and high resolution TEM that the growth dynamics at low temperatures is not governed by the well-known VLS mechanisms. Based on the Au-Zn phase diagram, temperature measurement and temperature size effects, we show that growth occurs via VSS. The precise composition of the Au-Zn catalyst nanoparticle has been determined to be $\gamma $-AuZn. Furthermore, we experimentally observe that there is an indication of a epitaxial relationship between the ZnO nanowires and the $\gamma $-AuZn seed particle. A critical new insight on the driving factor of VSS growth is proposed in which the VSS process occurs by a solid diffusion mechanism that is driven by a preferential oxidation process of the Zn inside the alloy catalyst induced by an epitaxial match between the ZnO(10-10) plane and the $\gamma $-AuZn(222) plane. [1] L. C. Campos et al, Adv. Materials (accepted for publication).