Nanoclusters and nanolines: the effect of molybdenum oxide substrate stoichiometry on iron self-assembly

O Lübben; S A Krasnikov; B Walls; N N Sergeeva; B E Murphy; A N Chaika; S I Bozhko; I V Shvets

doi:10.1088/1361-6528/aa6b50

Nanoclusters and nanolines: the effect of molybdenum oxide substrate stoichiometry on iron self-assembly

Nanotechnology. 2017 May 19;28(20):205602. doi: 10.1088/1361-6528/aa6b50. Epub 2017 Apr 4.

Authors

O Lübben¹, S A Krasnikov, B Walls, N N Sergeeva, B E Murphy, A N Chaika, S I Bozhko, I V Shvets

Affiliation

¹ School of Physics and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland.

PMID: 28375847
DOI: 10.1088/1361-6528/aa6b50

Abstract

The growth of Fe nanostructures on the stoichiometric MoO₂/Mo(110) and oxygen-rich MoO_2+x /Mo(110) surfaces has been studied using low-temperature scanning tunnelling microscopy (STM) and density functional theory calculations. STM results indicate that at low coverage Fe nucleates on the MoO₂/Mo(110) surface, forming small, well-ordered nanoclusters of uniform size, each consisting of five Fe atoms. These five-atom clusters can agglomerate into larger nanostructures reflecting the substrate geometry, but they retain their individual character within the structure. Linear Fe nanocluster arrays are formed on the MoO₂/Mo(110) surface at room temperature when the surface coverage is greater than 0.6 monolayers. These nanocluster arrays follow the direction of the oxide rows of the strained MoO₂/Mo(110) surface. Slightly altering the preparation procedure of MoO₂/Mo(110) leads to the presence of oxygen adatoms on this surface. Fe deposition onto the oxygen-rich MoO_2+x /Mo(110) surface results in elongated nanostructures that reach up to 24 nm in length. These nanolines have a zigzag shape and are likely composed of partially oxidised Fe formed upon reaction with the oxygen-rich surface.