TY - JOUR
T1 - Fabrication of Mo pyramidal-shape single atom tips covered by a noble metal
AU - Lin, Rung Jiun
AU - Chen, Yi Ju
AU - Chen, Hsiao Chi
AU - Fu, Tsu Yi
N1 - Funding Information:
The research is supported by National Science Council of Taiwan under grant nos. NSC 102-2112-M-003-012 and NSC 98-2112-M-001-027-MY3 .
PY - 2014/8/1
Y1 - 2014/8/1
N2 - The effect of annealing temperature on the faceting phenomena has been studied for pure molybdenum (Mo) and Mo tips covered with palladium (Pd), platinum (Pt), rhodium (Rh), or iridium (Ir) by field ion microscopy (FIM). For these Mo samples, three {2 1 1} facets were found to expand to {1 1 1} facets and form pyramidal structures after annealing at the temperature of 1100-1300 K. The pyramidal single atom tips (SATs) were formed on Pd-, Pt- and Rh-covered Mo tips. Two types of pyramidal structure, stacked by either 1, 3, 10 or 1, 6, 15 atoms for the top three layers were found. However, no SATs were found on pure Mo and Ir-covered tips. This indicates that noble metal adsorption, which can increase the difference of surface-free-energy anisotropy, indeed benefits the formation of SATs on Mo systems. Additionally, an SAT cannot be obtained for the Ir-covered Mo systems, because Ir is easily alloyed with Mo.
AB - The effect of annealing temperature on the faceting phenomena has been studied for pure molybdenum (Mo) and Mo tips covered with palladium (Pd), platinum (Pt), rhodium (Rh), or iridium (Ir) by field ion microscopy (FIM). For these Mo samples, three {2 1 1} facets were found to expand to {1 1 1} facets and form pyramidal structures after annealing at the temperature of 1100-1300 K. The pyramidal single atom tips (SATs) were formed on Pd-, Pt- and Rh-covered Mo tips. Two types of pyramidal structure, stacked by either 1, 3, 10 or 1, 6, 15 atoms for the top three layers were found. However, no SATs were found on pure Mo and Ir-covered tips. This indicates that noble metal adsorption, which can increase the difference of surface-free-energy anisotropy, indeed benefits the formation of SATs on Mo systems. Additionally, an SAT cannot be obtained for the Ir-covered Mo systems, because Ir is easily alloyed with Mo.
KW - Adsorbate-induced faceting
KW - Field ion microscope
KW - Molybdenum
KW - Single atom tips
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U2 - 10.1016/j.apsusc.2014.04.185
DO - 10.1016/j.apsusc.2014.04.185
M3 - Article
AN - SCOPUS:84901837724
SN - 0169-4332
VL - 309
SP - 90
EP - 94
JO - Applied Surface Science
JF - Applied Surface Science
ER -