Pd-D Systems Research Articles

Solid metal-hydrogen solutions with a symmetric miscibility gap

It is shown that the T-x projection of the miscibility gap in solid interstitial MeH x solutions will be symmetric and the pressure vs . temperature dependence of the corresponding isomorphic phase transformation will be determined by the reaction Me + ( z /2)H 2 = MeH z with a fixed z value attained at T → 0 K, if the mixing Gibbs energy of the solutions is a symmetric two-well function of the H content with a maximum at z /2. Based on these findings and using the literature data for the pure metal Me and the hydride MeH z , it is explained why the experimental dependences of the standard Gibbs energy for the isomorphic transformation between two solid phases of variable composition in the Pd–H and Pd-D systems ( z = 0.63) and in the Ni–H and Ni-D systems ( z = 1) are close to linear in the entire investigated temperature range. • Model of solid solutions Pd–H with a symmetric two-well mixing energy is considered. • The model explains the linear dependence ln P (1/ T ) for formation of palladium hydride. • The formation pressure is determined by the reaction Pd + ( z /2)H 2 = PdH z at z = 0.63 • Deviation of ln P (1/ T ) from linearity in this approximation is 1% at 194.5 ≤ T ≤ 565 K. • Similar results are obtained for the systems Pd-D, Ni–H, and Ni-D.

A theoretical study of weak interactions in phenylenediamine homodimer clusters.

Weak intermolecular interactions in phenylenediamine dimer (pdd) clusters are studied by dispersion-corrected density functional theory (DFT) calculations. Along with the optimization of geometric structures and the calculation of interaction energies, we employ molecular electrostatic potential (MEP) mapping, natural bond orbital (NBO) analysis and quantum theory of atoms in molecule (AIM) to analyze the origin and relative energetic contributions of the weak interactions in these pdd systems. It is revealed that the most stable o-phenylenediamine dimer (opdd) cluster is dominated by N-HN hydrogen bonds, the p-phenylenediamine dimer (ppdd) cluster is largely stabilized by N-Hπ and ππ stacking interactions, while the m-phenylenediamine dimer (mpdd) cluster is mainly held by a combination of n → π*, C-Hπ and C-HN interactions. Energy decomposition analysis (EDA) of the total interaction energies of these clusters further demonstrates that the weak intermolecular interactions are associated with electrostatic and dispersion contributions. Structural spectroscopic analysis is also addressed depicting the coexistence of multiple intermolecular interactions which give rise to the spectral variation in wavenumbers of the infrared and Raman activities. Insights into the weak interactions of pdds help us to understand the molecular mechanisms involved in biochemistry and self-assembly materials.

Pd-T (Palladium-Tritium)

The Pd-T phase diagram was not shown in [Massalski2]. Figure 1 shows the Pd-T phase diagram determined by [1985Las] by measuring pressure-temperature relationships during desorption cycles at various compositions. Table 1 shows Pd-T crystal structure data. Reference 1985Las: R. Lasser, Isotope Dependence of Phase Boundaries in the PdH, PdD, and PdT Systems, J. Phys. Chem. Solids, 1985, 46(1), p 33-37

1st PART of: Platinum and Palladium-Hydrogen: Thermodynamic Parameters of the Pd-H, Pd-D and Pd-T Systems

1st PART of: Platinum and Palladium-Hydrogen: Thermodynamic Parameters of the Pd-H, Pd-D and Pd-T Systems

Search for cold fusion in plasma-charged Pd-D and Ti-D systems

To investigate whether cold fusion of deuterium (D) can occur in solid Pd and Ti as proposed recently, we have searched for the D-D fusion reaction in plasma-charged Pd-D and Ti-D. In a small reaction cell, a DC glow-discharge was established in a deuterium gas between two electrodes, with a Pd or Ti sample placed on the cathode. A thin (50 A) Cu film was evaporated on the surface of the Pd samples to establish a barrier reducing the escape of D from the samples. Neutrons were detected with a liquid scintillator, and conventional pulse-shape discrimination technique was employed to distinguish gamma counts from neutron counts. No indication for a neutron count rate in excess of the natural background level was observed.

The origin of the inverse isotope effect in the PdH and PdD systems

Using the Eliashberg equation in the Matsubara representation, the calculation of T c for the PdH and PdD systems is performed under two schemes, and the inverse isotope effect is restudied. We conclude that the inverse isotope effect derives from the harmonicity of the lattice in most cases. In fact, there are more experiments to support our results.

The effect of isotopic substitution on the thermodynamic properties of palladium-hydrogen alloys

An attempt has been made to predict the thermodynamic properties of the Pd-D and Pd-T systems from those of the Pd-H system. By considering only the isotopic dependence of the optic modes, a satisfactory interpretation of the infinitely dilute solutions is not possible. However, using only the isotopic dependence of the optic modes together with an empirical equation for the infinitely dilute solution yields calculated results for the concentrated solutions in both the single and two phase regions which are in excellent agreement with the experimental results for the deuteride and tritide systems.

Isotope dependence of phase boundaries in the PdH, PdD, and PdT systems

The phase boundaries between the single phase regions α, β and the miscibility gap α + β were determined for the PdH, PdD, and PdT systems in the temperature ( T) range 40 ⩽ T ⩽ 160° C and concentration ( x = H atoms Pd atoms ) ranges 0.01 ⩽ x ⩽ 0.04, 0.54 ⩽ x ⩽ 0.60. The limits of the α-phase in the temperature-concentration plane are shifted to higher concentration values with increasing isotope mass of the hydrogen atoms in Pd, whereas the phase boundary between the α + β and β-regions is moved to lower concentration values in the sequence H, D, T. Although the experimentally observed phase boundaries shifts are small, the ratio of the phase boundary values for H, D and H, T can be described well by a simple harmonic model of the hydrogen atoms in Pd using the vibration frequencies determined by inelastic neutron scattering experiments.

Solubility of hydrogen isotopes in palladium

An all-metal facility has been built to handle about 1000 Ci of tritium for studies of the tritium behavior in metals. First measurements of the pressure-composition-temperature relationship for the palladium-tritium system $\mathrm{Pd}{\mathrm{T}}_{x}$ are reported for the pressure range $0.1\ensuremath{\le}p\ensuremath{\le}2$ bar, the composition range $0.02\ensuremath{\le}x\ensuremath{\le}0.65$, and the temperature range $35\ensuremath{\le}T\ensuremath{\le}125\ifmmode^\circ\else\textdegree\fi{}$C together with the results of the PdH and PdD systems measured under the same experimental conditions. The main conclusions are that the inequality ${p}_{{\mathrm{T}}_{2}}>{p}_{{\mathrm{D}}_{2}}>{p}_{{\mathrm{H}}_{2}}$ holds at equal concentrations and temperatures and that the $\ensuremath{\beta}\ensuremath{\rightarrow}\ensuremath{\alpha}$ transition enthalpies show a strong isotopic effect, whereas the entropies do not.

Palladium-tritium system

First measurements of the pressure-composition-temperature relationship for the palladium-tritium system are reported for the pressure range $0.1l~pl~2$. bar, the composition range $0.02l~xl~0.65$ (for $x$ in $\mathrm{Pd}{\mathrm{T}}_{x}$), and temperature range $35l~Tl~125\ifmmode^\circ\else\textdegree\fi{}$C. The PdH and PdD systems have also been measured using the same sample under the same experimental conditions. The main conclusions are that ${p}_{{\mathrm{T}}_{2}}g{p}_{{\mathrm{D}}_{2}}g{p}_{{\mathrm{H}}_{2}}$ at equal concentrations and temperatures, ${x}_{\mathrm{T}}l{x}_{\mathrm{D}}l{x}_{\mathrm{H}}$ at equal pressures and temperatures, and that the $\ensuremath{\beta}\ensuremath{\rightarrow}\ensuremath{\alpha}$ transition enthalpies show a strong, and the entropies a negligible, isotope dependence.

Superconductivity in PdH, PdD and PdAgD systems

The possible mechanisms of superconductivity in PdH(D) and PdAgH(D) systems which have been studied by Buckel and Stritzker are discussed. Especially we examine the possible participation of the optical phonon modes in the electron-phonon coupling and their importance for the observed opposite isotope effect in these systems.

Theory for superconductivity in Pd-H and Pd-D systems

A theory is presented explaining the recently observed superconductivity at 9 °K in Pd-H and at 11 °K in Pd-D as due to the quenching of the spin-fluctuations and as due to the decrease of the Coulomb pseudo-potential μ present in Pd. That one observes for PdD a larger superconducting transition temperatureT c than for PdH is explained by the larger lattice expansion resulting for adding H to Pd. The observed non-monotonic dependence ofT c on the Hydrogen concentration is explained by the fact that approximately λ ∝N(0) for smallN(0), whereN(0) is the electronic density of states at the Fermi-energy and where λ denotes the electron-phonon coupling constant. Superconducting transition temperatures are estimated for PtH and RhH.

The magnetic susceptibility of Pd, PdH and PdD between 4 and 300 K

Measurements have been made of the magnetic susceptibility of PdH and PdD alloys over the temperature range between 4K and 300K. A series of specimens was studied with composition ranging from 0.0 to 0.7 H or D atoms/Pd atom. The results are interpreted in terms of the two phase nature of the PdH and PdD systems. For the alpha phase the susceptibility is large and varies with temperature in a manner similar to that of pure palladium, while the susceptibility of the beta phase is slightly diamagnetic and almost independent of temperature. The temperature dependence of the susceptibility of both pure Pd and alpha phase PdH agrees well with a theoretical relation given by Misawa (1970) based on treating the electrons in palladium as a nearly ferromagnetic Fermi liquid.

Superconductivity in the palladium-hydrogen and the palladium-deuterium systems

Superconducting transitions have been observed in the Pd-H and Pd-D systems up to temperatures of 9 and 11 K, respectively. The high concentrations necessary for superconductivity have been obtained by implanting H- or D-ions into the Pd at liquid helium-temperatures.

Principles of PD Recording Systems and their Use in Photofabrication

This paper begins with a review of various methods of obtaining physically developable latent images. The more extensively discussed PD-D and PD-R systems have in common that the latent image is produced by indirect nucleation. In PD-D systems silver amalgam nuclei are formed by a disproportionation reaction during or after exposure: in PD-R systems metal nuclei, e.g., those consisting of silver, palladium, platinum or gold, are formed by reduction during or after exposure. Examples are given of the physical developers, and the factors determining stability and speed are discussed. Electroless coppering solutions are included and the effect of deposition rate and temperature on the ductility of copper deposits is considered. The influence of polyethylene glycols on the deposition rate and ductility is illustrated. PD-D photoplating based on photosensitive diazosulphonate and PD-R photoplating on Tio2/adhesive layers and the production machines are described.