Armanet/Bonnard (i2-HMR ): Palladium-Hydrogen System (Pd-H) : Expected and Unexpected Behavior Following H Loading at Room Temperature and Explanation

During RNBE-2016 in Avignon, there as a very technical presentation about PdH system, and hydrides behavior.

Here is an english summary of the presentation by Nicolas Armanet & Michel Bonnard or i2-HMR), and the French version.
Their institute i2-HMR is dedicated to hydrogen in materials (not to LENR).

Armanet_N_En.pdf
Armanet_N_Fr.pdf

Here is the french presentation made ar RNBE2016
https://drive.google.com/file/…KOG40RHc/view?usp=sharing

On this subject Cobraf dug 2 more papers :
One by hagelstein (the one supported by industrial heat)
http://www.iscmns.org/CMNS/JCMNS-Vol17.pdf#page=72

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O-site and T-site Occupation of α-phase PdHx and PdDx

An important study of the solubility of hydrogen in α-phase PdHx and deuterium in α-phase PdDx over a wide temperature range was published by Clewley et al. (J. Chem. Soc., Faraday Trans. 1: Phy. Chem. Condensed Phases 69 (1973) 449–458). An analysis of the data based on an empirical solubility model based on O-site occupation allows for an understanding of the data at low temperature, but probably is not a good starting place for understanding the solubility at high temperature. We have applied a recently developed empirical model for both O-site and T-site occupation to this data set, and find good agreement between data and a basic version of the model which assumes that the O-site and T-site partition functions are taken to be harmonic oscillator partition functions. Even better agreement is obtained when a more realistic O-site partition function is used. A range of optimum models with different assumptions about the T-site partition function is considered, and it is found to be possible to select one that matches the T-site occupation at zero loading inferred from neutron diffraction measurements of Pitt and Gray (Europhys. Let. 64 (2003) 344). The O-site to T-site excitation energy is assumed independent of temperature in these models, and we obtain specific model values of 105.3 meV for α-phase PdDx and 106.5 meV for α-phase PdHx .

another is by what looks like a mainstream team in japan :

http://pubs.acs.org/doi/abs/10.1021/jacs.6b04970

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Nanometer-Size Effect on Hydrogen Sites in Palladium Lattice

Nanometer-sized materials attract much attention because their physical and chemical properties are substantially different from those of bulk materials owing to their size and surface effects. In this work, neutron powder diffraction experiments on the nanoparticles of palladium hydride, which is the most popular metal hydride, have been performed at 300, 150, and 44 K to investigate the positions of the hydrogen atoms in the face-centered cubic (fcc) lattice of palladium. We used high-quality PdD0.363 nanocrystals with a diameter of 8.0 ± 0.9 nm. The Rietveld analysis revealed that 30% of D atoms are located at the tetrahedral (T) sites and 70% at the octahedral (O) sites. In contrast, only the O sites are occupied in bulk palladium hydride and in most fcc metal hydrides. The temperature dependence of the T-site occupancy suggested that the T-sites are occupied only in a limited part, probably in the subsurface region, of the nanoparticles. This is the first study to determine the hydrogen sites in metal nanoparticles.

There is recently the publication of an interesting paper on Hydrogen in palladium nano-particles

http://dx.doi.org/doi:10.1038/ncomms14020

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Direct visualization of hydrogen absorption dynamics in individual palladium nanoparticles

Many energy storage materials undergo large volume changes during charging and discharging. The resulting stresses often lead to defect formation in the bulk, but less so in nanosized systems. Here, we capture in real time the mechanism of one such transformation—the hydrogenation of single-crystalline palladium nanocubes from 15 to 80 nm—to better understand the reason for this durability. First, using environmental scanning transmission electron microscopy, we monitor the hydrogen absorption process in real time with 3 nm resolution. Then, using dark-field imaging, we structurally examine the reaction intermediates with 1 nm resolution. The reaction proceeds through nucleation and growth of the new phase in corners of the nanocubes. As the hydrogenated phase propagates across the particles, portions of the lattice misorient by 1.5%, diminishing crystal quality. Once transformed, all the particles explored return to a pristine state. The nanoparticles’ ability to remove crystallographic imperfections renders them more durable than their bulk counterparts.