Faceting and the orientational phase diagram of stepped Pt(001) surfaces

Journal Article · Wed Jun 15 04:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.16702· OSTI ID:7275707

Yoon, M; Mochrie, S G.J. ^[1]; Zehner, D M ^[2]; Watson, G M; Gibbs, D ^[3]

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1. Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States)
2. Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6057 (United States)
3. Physics Department, Brookhaven National Laboratory, Upton, New York, 11973-5000 (United States)

The results of synchrotron-x-ray-scattering studies of stepped Pt(001) surfaces are reported. An orientational phase diagram is proposed for Pt surfaces between the cubic (001) orientation and orientations tilted 6[degree] away from the [001] direction towards the [110] direction, and for temperatures between 300 and 1850 K. Four distinct orientational phases are identified. At the highest temperatures, we find a one-phase region in which the surface is rough with the local surface normal equal to the macroscopic surface normal. Below [ital T][sub 0]=1820 K, hexagonally reconstructed (001) facets appear in coexistence with the tilted rough phase. The phase boundary of the rough phase decreases with temperature as a quadratic function of the tilt angle away from the [001] direction, consistent with simple theoretical ideas. Below [ital T][sub 1]=1630 K, there are two symmetry-related 2[degree] magic vicinal phases with azimuthal orientations symmetrically rotated away from the cubic [110] direction by [plus minus]4.8[degree]. The 2[degree] magic vicinals are reconstructed, so that the terraces between their constituent steps form a corrugated and rotated quasihexagonal structure. Remarkably, the steps are parallel to the troughs and crests of the corrugation. In addition, the tilt angle appears closely related to the period of the reconstruction, favoring an integer (3 or 4) or half integer (9/2 or 7/2) number of corrugation periods on each terrace between steps, depending on the temperature. Finally, below [ital T][sub 2]=1590 K, we find the 6[degree] magic vicinal phase. Its microscopic structure involves terraces upon which there is one period of the surface corrugation.

• DOE Contract Number: AC02-76CH00016; AC05-84OR21400
• OSTI ID: 7275707
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 49:23; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
BREMSSTRAHLUNG
CRYSTAL FACES
DIAGRAMS
ELECTROMAGNETIC RADIATION
ELEMENTS
METALS
PHASE DIAGRAMS
PLATINUM
PLATINUM METALS
RADIATIONS
SURFACE PROPERTIES
SYNCHROTRON RADIATION
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
TRANSITION ELEMENTS