NMR comparisons of nanocrystalline and coarse-grained palladium hydride and deuteride.

Journal Article · Sat Feb 01 04:00:00 EST 2003 · Phys. Rev. B

OSTI ID:961182

Eastman, J A

Two distinct proton NMR lines were previously reported in nanocrystalline PdH{sub x} (r=5nm, x=0.70), and were tentatively assigned to H in the crystalline cores and in grain boundaries. Here we show this assignment to be incorrect, with all of the H in the Pd forming a single line and the second line arising from surface-bound H{sub 2}O formed by reaction with an initial oxygen surface layer on the Pd. Distinct spectroscopic signatures of deuterium in boundaries and in crystalline cores are sought in the rigid lattice {sup 2}D spectrum of nano-PdD{sub x} and in the onset of motional narrowing. In neither case is two-part behavior found; the results are nearly identical to those in coarse-grained PdD{sub x}. The spin-lattice relaxation rate R{sub 1} of {sup 2}D in nano-PdD{sub x} is compared to that in coarse-grained material. The electronic (Korringa) contribution, dominant below 125 K, is 1.58 times as large in nano-PdD{sub x}, indicating a substantial difference in the electronic structure in the boundary regions of nano-PdD{sub x}. Above 200 K, a contribution to R{sub 1} from exchange with D{sub 2} gas and/or surface adsorbed species is observed for nano-PdD{sub x}, a result of the large surface area.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; NSF
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 961182
• Report Number(s): ANL/MSD/JA-45298
• Journal Information: Phys. Rev. B, Journal Name: Phys. Rev. B Journal Issue: 5 ; Feb. 1, 2003 Vol. 67; ISSN 1098-0121
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COMPARATIVE EVALUATIONS
DEUTERIDES
DEUTERIUM
ELECTRONIC STRUCTURE
GRAIN BOUNDARIES
LAYERS
NUCLEAR MAGNETIC RESONANCE
OXYGEN
PALLADIUM HYDRIDES
PROTONS
SPIN-LATTICE RELAXATION
SURFACE AREA
SURFACES