| AVS 64th International Symposium & Exhibition | |
| 2D Materials Focus Topic | Tuesday Sessions |
| Session 2D-TuA |
| Session: | Growth of 2D Materials |
| Presenter: | Ann Lii-Rosales, Iowa State University and Ames Laboratory |
| Authors: | A. Lii-Rosales, Iowa State University and Ames Laboratory P.A. Thiel, Iowa State University and Ames Laboratory |
| Correspondent: | Click to Email |
In this study, we use STM to investigate the intercalation of atomic metals, copper (Cu) and dysprosium (Dy), in the surface of graphite that is pre-treated with Ar+ bombardment.
Surface intercalated Dy rafts have a characteristic height of 0.61 ± 0.03 nm, with structured moiré patterns atop faceted rafts. DFT calculations on intercalated Dy rafts support our experimental observation: instead of a dilute, (√3×√3)R30° arrangement of Dy atoms as in the well-known stage-1 Dy graphite intercalation compound (GIC), our Dy rafts are dense and are composed of three contiguous layers of Dy sandwiched between graphitic layers.
In the case of Cu, for which no bulk GIC’s are known, we achieve surface intercalation of Cu in ion-bombarded graphite. Spanning temperatures of 600 – 900 K, the morphology of intercalated Cu responds sensitively. At 600 – 800 K, intercalated Cu forms faceted islands that are variable in heights, ranging from 1.7 nm to as tall as 35 nm. At 850 K, intercalated Cu no longer forms faceted islands; instead, round clusters ranging from ~0.3 nm to 10 nm tall are present. At 900 K, small and round features ~0.3 nm tall prevail. Larger clusters are presumably removed by desorption. High resolution imaging atop a Cu island sheds light on the number of carbon overlayers and shifting in the stacking sequence of carbon lattice, potentially due to strain as a result of intercalation.
Relative to known bulk GIC’s, our work shows that metals on graphite surfaces adopt configurations that are different in two ways. First, the metals form dense intercalated surface islands; and second, metals which do not intercalate in the bulk can do so on the surface. Surface intercalation of other metals can be envisioned.
This work is supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division through the Ames Laboratory, which is operated by Iowa State University under contract # DE-AC02-07CH11358.