Trends in the electron-phonon coupling parameter in some metallic hydrides
We present an evaluation of the electron-phonon coupling parameter lambda, using the McMillan formalism, for several classes of stoichiometric mono- and dihydrides with a metallic underlying fcc structure. We calculate the electronic term eta and use experimental estimates for the phonon energies when available. We derive systematic trends concerning both contributions to eta stemming, respectively, from the metallic site M and the hydrogen site H. We show that eta/sub H/ is generally small, but it may become large if the Fermi energy is in the metal s-p band as in the filled d-band transition-metal (TM) hydrides such as PdH; eta/sub H/ may also be large when a metal-hydrogen antibonding band crosses the Fermi level, a case which happens in AlH and may happen for some unstable dihydrides. The metallic contribution eta/sub M/ is calculated to be small for all stable mono- and dihydrides like PdH, NiH, ZrH/sub 2/, NbH/sub 2/, etc., but nothing in principle prevents this contribution from becoming as large as in some pure TM, if one sweeps the Fermi level through the whole metallic d band. Good agreement with the available experimental data is obtained concerning the occurrence of superconductivity in the compounds considered.
- Research Organization:
- Centre de Mecanique Ondulatoire Appliquee du Centre National de la Recherche Scientifique, 23 rue du Maroc, 75019 Paris, France
- OSTI ID:
- 5819114
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Vol. 24:12
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
METALS
ELECTRON-PHONON COUPLING
ELECTRONIC STRUCTURE
SUPERCONDUCTIVITY
FCC LATTICES
FERMI LEVEL
HYDRIDES
LATTICE VIBRATIONS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY LEVELS
HYDROGEN COMPOUNDS
PHYSICAL PROPERTIES
360204* - Ceramics
Cermets
& Refractories- Physical Properties
656101 - Solid State Physics- Superconductivity- General Theory- (-1987)