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Nanopowder diffraction analysis beyond the Bragg law applied to palladium
Author(s) -
Kaszkur Zbigniew
Publication year - 2000
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s002188989901290x
Subject(s) - chemisorption , palladium , diffraction , materials science , lattice constant , cluster (spacecraft) , cluster size , neutron diffraction , attenuation , transition metal , molecular physics , analytical chemistry (journal) , condensed matter physics , crystallography , chemistry , optics , molecular dynamics , computational chemistry , adsorption , physics , catalysis , biochemistry , chromatography , computer science , programming language
A method of powder diffraction analysis is proposed that is applicable to transition metal nanoparticles and which has been applied to palladium. From results of simulations it is shown that: ( a ) the overall average lattice constant of small transition metal clusters decreases with decreasing size of the cluster as a result of surface contraction; ( b ) the shift of a diffraction peak position driven by chemisorption increases monotonically with the decrease of cluster size and can be used for the estimation of cluster size; ( c ) the peak broadening of small clusters may be larger than that resulting from their size; the additional contribution originates from a high density of defects; ( d ) the extent of the microstrain may be evaluated from the peak broadening and the rate of attenuation of peak intensity; ( e ) the intensity scattered by small palladium clusters indicates significant surface disorder that may vary during a change of gas atmosphere and during chemisorption of oxygen at the surface.