Synchrotron x-ray study of physisorbed films of mixtures of Ar and Xe on graphite

Conference · Thu Jul 01 04:00:00 EDT 1982

OSTI ID:5078141

Bohr, J; Nielsen, M; McTague, J P; Als-Nielsen, J; Kjaer, K

Mixtures of Ar and Xe have been studied in most of the submonolayer region of the phase diagram (T,chi,rho), T = temperature, chi = chemical composition, rho = fraction of a monolayer. The basic feature is a large tendency to form ..sqrt.. 3 x ..sqrt.. 3 commensurate alloys (Kr-like structures), but none of the commensurate nor of the incommensurate structures form a chemically ordered alloy at 11 K. Thus the 2D solid can be thought of as a solid consisting of particles of an average size. This allows the study of commensurate-incommensurate phase transition driven by average particle size. The transition is indeed a sharp first order transition taking place through coexisting phases (tau/sub A/ = 1.64 A/sup -1/ and tau/sub B/ = 1.703 A/sup -1/), as was the case for the low temperature pure Kr-system. Another interesting feature is the existence of well correlated liquid-like structures which preserve their correlation over a temperature range of 5 Kelvin or more. This unusual behavior is for chemical compositions where there is coexistence of a commensurate and an incommensurate solid at high temperature.

• Research Organization: Brookhaven National Lab., Upton, NY (USA); Risoe National Lab., Roskilde (Denmark)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5078141
• Report Number(s): BNL-31578; CONF-820744-1; ON: DE82019349
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
ARGON
CARBON
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIAGRAMS
ELEMENTAL MINERALS
ELEMENTS
FILMS
FLUIDS
GASES
GRAPHITE
INTERSTITIALS
MINERALS
NONMETALS
PHASE DIAGRAMS
POINT DEFECTS
RARE GASES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
XENON