Ab initiostudy of the adsorption, migration, clustering, and reaction of palladium on the surface of silicon carbide

Abstract

This work presents first principle calculations to understand the adsorption, clustering, migration, and reaction of Pd on three different surfaces of . The surfaces were chosen based upon experimental and theoretical work. Pd preferably binds to Si-terminated surfaces and has higher migration energies on these surfaces. Pd has low migration energies on non-Si-terminated surfaces facilitating the creation of Pd clusters. About 0.5 eV is gained per Pd atom added to a cluster. Reaction mechanisms are reported for Pd reacting on {100} surfaces. On the {100} C-terminated surfaces, a single Pd atom can substitute for a C with an energy barrier of 0.48 eV and two Pd atoms can substitute for two C atoms with an energy barrier of 0.04 eV. In both cases, the Pd atoms form Pd-C-C bridges between Si lattice sites. For the {100} Si-terminated surface, a single Pd atom can substitute for a Si atom with an energy barrier is 1.53 eV. No comparable low energy pathways were found on the {111} surface.

Analytical bond-order potential for silver, palladium, ruthenium and iodine bulk diffusion in silicon carbide

“…This invisible diffusion through single crystalline SiC coincidences with our observation of insufficient interstitial mechanism in bulk under pure thermal condition, whereas grain boundary could be a fast path suggested by the experiment. Also, palladium can transform SiC into palladium silicide without irradiation at relative low temperatures [70], meaning that other reaction paths might play an important role, such as reactions involving interface between Pd and SiC [71,72]. As indicated previously, ruthenium and iodine are characterized by large migration energies, and thus, might be trapped inside the bulk SiC.…”

Palladium clusters, free and supported on surfaces, and their applications in hydrogen storage

“…107,108 To understand these processes, Schuck and Stoller performed DFT studies on the adsorption, migration and clustering of palladium on the surface of SiC, and they were also interested in the reaction between Pd and the substrate. 109 Reconstructed Si-terminated (111), C-terminated (100), and Si-terminated (100) surfaces of SiC were considered. Pd can bind to several sites on each of these three surfaces, and the adsorption binding energies are higher in the Si-terminated (100) surface as compared to the other two, by 2.5–3.0 eV.…”

“…But adsorption of Pd clusters directly on NiAl surfaces has also been investigated. 109 Bulk NiAl crystals have the CsCl structure. The (100) surface of NiAl, which is the most stable one, reconstructs and forms ripples, with the Al rows of the first layer displaced vertically outwards by 0.16 Å with respect to the Ni rows.…”

A Novel Dual-Step Nucleation Pathway in Crystalline Solids under Neutron Irradiation

“…The near homogenous distribution of these nanoscale Pd rich precipitates in β-SiC matrix 19 , 20 has led to obvious conclusion based on classical nucleation theory to date that Pd interacts with β-SiC to form these precipitates. Hence, there have been numerous modeling effort to simulate the intragranular Pd transport in TRISO fuel by studying the interaction of Pd with β-SiC 21 – 23 . However, Gentile et al .…”