Electronic structure, bonding and chemisorption in metallic hydrides

Conference · Tue Jan 01 00:00:00 EST 1980

DOI:https://doi.org/10.1016/0022-5088(80)90359-8· OSTI ID:5691151

Ward, J W

Problems that can arise during the cycling steps for a hydride storage system usually involve events at surfaces. Chemisorption and reaction processes can be affected by small amounts of contaminants that may act as catalytic poisons. The nature of the poisoning process can vary greatly for the different metals and alloys that form hydrides. A unifying concept is offered, which satisfactorily correlates many of the properties of transition-metal, rare-earth and actinide hydrides. The metallic hydrides can be differentiated on the basis of electronegativity, metallic radius (valence) and electronic structure. For those systems where there are d (transition metals) or f (early actinides) electrons near the Fermi level a broad range of chemical and catalytic behaviors are found, depending on bandwidth and energy. The more electropositive metals (rare-earths, actinides, transition metals with d < 5) tend to strongly chemisorb electrophilic molecules; this is a consequence of the manner in which new bonding states are introduced. More electronegative metals (d >> 5) dissolve hydrogen and form hydrides by an electronically somewhat different process, and as a class tend to adsorb electrophobic molecules. The net charge-transfer in either situation is subtle; however, the small differences are responsible for many of the observed structural, chemical, and catalytic properties in these hydride systems.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5691151
• Report Number(s): LA-UR-80-458; CONF-800402-8; TRN: 80-005704
• Resource Relation: Journal Volume: 73; Journal Issue: 1; Conference: International symposium on the properties and applications of metal hydrides, Colorado Springs, CO, USA, 7 Apr 1980
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
08 HYDROGEN
HYDRIDES
ELECTRONIC STRUCTURE
HYDROGEN STORAGE
METALS
ALLOYS
BAND THEORY
BONDING
CHEMISORPTION
COBALT
EUROPIUM
HAFNIUM
IRON
LANTHANUM
NICKEL
PALLADIUM
RUTHENIUM
SCANDIUM
SURFACES
TITANIUM
TUNGSTEN
YTTERBIUM
YTTRIUM
ZIRCONIUM
CHEMICAL REACTIONS
ELEMENTS
FABRICATION
HYDROGEN COMPOUNDS
JOINING
PLATINUM METALS
RARE EARTHS
REFRACTORY METALS
SEPARATION PROCESSES
SORPTION
STORAGE
TRANSITION ELEMENTS
360104* - Metals &amp; Alloys- Physical Properties
080201 - Hydrogen- Chemisorption Storage