Oxygen-induced nano-faceting of Re(112¯1)

Abstract

Abstract We report results from a detailed study of oxygen-induced faceting of Re( 11 2 ¯ 1 ) using low energy electron diffraction (LEED). Depending on conditions for reaction with oxygen, the initially planar Re( 11 2 ¯ 1 ) surface evolves sequentially to form zigzag chains consisting of ( 01 1 ¯ 0 ) and ( 10 1 ¯ 0 ) facets that coexist with stepped ( 11 2 ¯ 1 ) plateaus; three-sided pyramids exposing ( 01 1 ¯ 0 ), ( 10 1 ¯ 0 ) and ( 33 6 ¯ 4 ) facets; a faceted surface with five facets including ( 01 1 ¯ 0 ), ( 10 1 ¯ 0 ), ( 11 2 ¯ 2 )-(2 × 1), ( 01 1 ¯ 1 )-(2 × 1) and ( 10 1 ¯ 1 )-(2 × 1); and four-sided pyramids exposing { 01 1 ¯ 0 } and { 01 1 ¯ 1 }-(2 × 1) facets. We have observed reversible morphological transitions between the faceted surfaces and discovered that each intermediate facet in the evolutionary chain contains microscopic structural elements of the preceding and following facets, which may provide a natural explanation for the microscopic mass transport pathways in the morphological evolution. Scanning tunneling microscopy (STM) data confirm the morphology of faceted surfaces and give complementary information to LEED results.