A model of structural disorder and size distribution for palladium supported on pumice

A model of size distribution and structural disorder for palladium grown on pumice is developed. The model parameters are determined by fitting the simulated powder pattern to the experimental data. Three samples, characterized by 2.4, 1.14 and 0.86 wt.% Pd respectively were examined. The results point to nearly spheroidal crystallites, with sizes ranging from 40 to 20 Å, affected by stacking faults in the sequence of the close-packed (111) layers to an extent independent of size and by intralayer second-kind distortions. A comparison with the results obtained following classical procedures is supplied. In the Appendix a new approach for the determination of growth stacking faults from peak shifts is presented.