Deuterium in Palladium 6th International workshop on Anomalies in hydrogen/deuterium loaded metals 13-15 May Siena Energetics Technologies Ltd. Omer, Israel Deuterium in Palladium Structural transformations in Pd

A typical view surface of Pd foil after rolling and annealing Basic features of the structure: i-equi-axial grains, ii-twins formation as a result of a plastic deformation iii-chains of the stacking faults at twin boundaries are the effective traps for D+ ions. Triple twins

Twin formation - Outline. Twinning plane is {111} in fcc crystals Twin formation - Outline. Twinning plane is {111} in fcc crystals. Slip planes and directions at plastic deformations are closed packed plains and directions.

Alternation of closed pack layers in fcc structure Regular alternation Alternation in twins C C A B B A C C B B A A

TEM image of Pd foil. Dislocation contrast. Dislocation density 5.1010 cm-2

Plastic deformation of Pd poly-crystal during dissolution of deuterium (electrolysis in heavy water solution) Again the slip surfaces are {111}. Plastic deformation of Pd occurs at deuterium dissolution due to significant change of lattice volume. <110> <110> {111}

Pd mass transfer during electrolysis A surface of Pt contact wire after an electrolysis with an inclusion Pd-Pt solid solution. Driving forces of Pd surface mass-transfer during the electrolysis: i-heterogeneous character of the cathode containing thin Pt film on a surface, ii-decrease of free energy of system due to formation of Pd-Pt alloys.

Selective sputtering of Pd surface in D glow discharge Formation of new structure of a surface occurs due to an anisotropy of sputtering rates on the planes with various crystallographic indexes. The sputtering rate is less for the planes of higher bond energy between atoms. As a rule, higher bond energy is characteristic for planes with maximal reticular density of atoms. {111} planes are such planes for fcc structure. Octahedrons are faceted by these planes. Therefore the octahedrons are main polyhedron of "weathering” Pd.

Joint action of D+ GD plasma and cathodic treatment These surfaces are the result of selective sputtering at the bombardment by ions D+ (GD) and the subsequent deuterium absorption, accompanied by Pd "swelling". Periodic character of sputtering and multi-layered structure of the pyramids. Multi-level character of the structural organization of the surface and the concurrence of a sputtering of various planes are seen.

Anisotropy of D absorption at cathodic polarization in the heavy water Anisotropy of D absorption at cathodic polarization in the heavy water. High current density. Steep gradient of D absorption rate at boundaries of twin lamella

Role of grain boundaries in D2 absorption C12 H+ Pt194.96 SIMS images of Pd sample (#64) after cathodic treatment in a heavy water. Scale bar-10 um

Role of grain boundaries in D2 absorption (cont.) Primary absorption of deuterium at grain boundaries of Pd during cathodic treatment in a heavy water solution.

A hierarchy of structural transformations of Pd surface A hierarchy of structural transformations of Pd surface. Group transformation. Etching in D+ GD plasma After rolling and annealing After rolling and annealing

Embrittlement of Pt contact wire due to deuterium absorption. X-ray spectra of Pt wire