Structure and reactivity of LaB[sub 6](100)
The structure of LaB[sub 6](100) was studied using scanning tunneling microscopy, and the reactivity of the surface with O[sub 2] and D[sub 2]O was studied using temperature programmed desorption. The surface that is observed has a square lattice of lanthanum atoms having a 4 [angstrom] spacing with approximately 10% of the La surface sites vacant. As indicated by a weak atomic corrugation of only 0.2 [angstrom], the electronic states near the Fermi level display a degree of dislocalization typical of a metal. On a larger scale, the surface consists of (100) terraces with an average width of 125 [angstrom] separated by steps one unit cell high. Evaporation of the LaB[sub 6](100) surface appears congruent with a heat of vaporization of 570 kJ/mol. LaB[sub 6](100) is observed to react with O[sub 2] and D[sub 2]O to form LaO BO, and B[sub 2]O[sub 2]. LaO exhibits zero order desorption kinetics with a heat of desorption of 790 kJ/mol. BO and B[sub 2]O[sub 2] show first order desorption with heats of desorption of about 300 and 230 kJ/mol, respectively.
- Research Organization:
- Illinois Univ., Chicago, IL (United States)
- OSTI ID:
- 7045330
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
BORIDES
BORON COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DESORPTION
ENERGY
LANTHANUM BORIDES
LANTHANUM COMPOUNDS
MICROSCOPY
MICROSTRUCTURE
RARE EARTH COMPOUNDS
SORPTION
SURFACE PROPERTIES