Growth and thermal stability of Ag or Au films on Nb(110)

Journal Article · Mon Aug 15 00:00:00 EDT 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.38.2959· OSTI ID:6927339

Ruckman, M W; Jiang, L

The growth and thermal stability of ultrathin (<50-A-thick) Ag and Au films on Nb(110) was investigated with use of photoemission spectroscopy and low-energy electron-diffraction (LEED) patterns. The LEED results show that Ag or Au forms a monolayer which is commensurate with the substrate, but also show that the structure of this overlayer reverts to a more close-packed structure after three monolayers (ML) have been deposited. Photoemission spectra show trends that suggest the evolution of the Ag or Au band structure with coverage and also show that a surface deposit of at least 2 ML of Ag or Au is required to observe valence-band states characteristic of the bulk metal. Further examination of the photoemission spectra suggests that the Ag or Au d-band states play only a small role in the chemical bonding that occurs between the noble metals and Nb(110), and this can be contrasted with the extensive d-band involvement in chemisorption bonds formed between Pd or Pt and Nb(110). Heating does not cause substantial change in the electric structure of 12.8-ML-thick Ag films and they thermally desorb from Nb when heated above 830 K. Similar Au films intermix with Nb to form a disordered surface phase when heated beyond 750 K. Desorption or complete in-diffusion of Au occurs when the substrate is heated beyond 1100 K. Implications for the formation of strained surface layers and surface chemical properties of noble metals on Nb(110) are discussed.

• Research Organization: Brookhaven National Laboratory, Upton, New York 11973-5000
• OSTI ID: 6927339
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 38:5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
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ELECTRONIC STRUCTURE
NIOBIUM
COATINGS
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CHEMICAL BONDS
DESORPTION
ELECTRON DIFFRACTION
FILMS
GROWTH
PHOTOELECTRON SPECTROSCOPY
STABILITY
SURFACES
VERY HIGH TEMPERATURE
COHERENT SCATTERING
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
METALS
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TRANSITION ELEMENTS
360104* - Metals &amp; Alloys- Physical Properties