Pd Interlayer Research Articles

Effects of amorphization and interlayer on the hydrogen storage properties of multi-component Ti-V-Zr-Nb-M (M = Mg, Al) alloy films

In this work, hydrogen storage properties of the multi-component amorphous Ti-V-Zr-Nb-M (M = Mg, Al) alloy films as prepared by a magnetron sputtering method are studied. In addition, the impact of different Pd layer numbers on the microstructure, morphology and hydrogen storage properties of the Ti-V-Zr-Nb alloy film is also investigated. The film retains an amorphous structure after hydrogen absorption and desorption, the hydrogenation capacity of the amorphous Ti-V-Zr-Nb alloy film reaches about 0.50 wt% at room temperature without activation and can release 0.18 wt% hydrogen at 250 ℃, the addition of lightweight elements Mg and Al improves the hydrogen absorption and release properties. Secondly, when the inserted Pd interlayers are increased from 2 to 10 layers, the dehydrogenation properties of Ti-V-Zr-Nb amorphous films are improved. The reduction in film thickness reduces the film sizes, and together with the Pd layers accelerates the dissociation and diffusion of hydrogen, both of these characteristics contribute to the improvement of dehydrogenation properties.

Improving the Hydrogen Oxidation Reaction Rate of Ru by Active Hydrogen in the Ultrathin Pd Interlayer.

Enhancing the catalytic activity of Ru metal in the hydrogen oxidation reaction (HOR) potential range, improving the insufficient activity of Ru caused by its oxophilicity, is of great significance for reducing the cost of anion exchange membrane fuel cells (AEMFCs). Here, we use Ru grown on Au@Pd as a model system to understand the underlying mechanism for activity improvement by combining direct in situ surface-enhanced Raman spectroscopy (SERS) evidence of the catalytic reaction intermediate (OHad) with in situ X-ray diffraction (XRD), electrochemical characterization, as well as DFT calculations. The results showed that the Au@Pd@Ru nanocatalyst utilizes the hydrogen storage capacity of the Pd interlayer to "temporarily" store the activated hydrogen enriched at the interface, which spontaneously overflows at the "hydrogen-deficient interface" to react with OHad adsorbed on Ru. It is the essential reason for the enhanced catalytic activity of Ru at anodic potential. This work deepens our understanding of the HOR mechanism and provides new ideas for the rational design of advanced electrocatalysts.

Role of Pd interlayer on NiTi to Ti6Al4V laser welded joints: Microstructural evolution and strengthening mechanisms

Obtaining a reliable NiTi to Ti6Al4V dissimilar joint exhibiting NiTi's superelasticity can provide design flexibility in aerospace and biomedical fields via integrating distinct material benefits. However, this materials couple is vulnerable to severe embrittlement due to the development of excessive intermetallic compounds (IMCs), namely Ti2Ni. Pd-free and Pd-interlayered NiTi-Ti6Al4V laser joints were evaluated for their microstructure, compositional changes, thermodynamic mechanism, and mechanical properties. The presence of Pd constrained the formation of Ti2Ni IMC, and NiTi-Ti6Al4V joints with excellent mechanical properties demonstrating superelastic behavior were achieved for the first time. The tensile strength and rupture strain of the Pd-added NiTi-Ti6Al4V joint improved more than twofold, reaching 520 MPa and 5.6%, respectively. During cyclic tensile testing, the Pd-added joint demonstrated superelasticity and a comparable irrecoverable strain to NiTi (1 versus 0.65%). Multiscale characterization revealed that the fraction of Ti2Ni decreased from 83 to 10% near the NiTi boundary and 24 to 6% at the weld center compared to the Pd-free joint. The superior thermodynamic formation tendency of Ti-Pd compounds over Ti2Ni IMC favored their development, and thus Ti-Pd and NiTi compounds dominated the fusion zone (FZ) at the expense of Ti2Ni IMC, explaining the improved mechanical performance of the Pd-added joint.

Diffusion bonding of Ti‐coated Cf‐SiCf/SiBCN composites to Nb using Ag–Pd interlayer

AbstractThe Ti‐coated Cf‐SiCf/SiBCN ceramic was diffusion‐bonded to Nb using an Ag–Pd interlayer. At a ceramic/Ag–Pd interface, it is found that Ti first reacted with C and Pd to form a TiCx/Ti(Pd) double‐layer structure, and then Ti(Pd) completely converted into TiCx with the increase of holding time or temperature. Meanwhile, the infiltration of Pd along TiCx grain boundary reacted with Si to form brittle Pd2Si compound. By contrary, only a simple NbPd3 layer was formed at the Nb/Ag–Pd interface during the whole process. A maximum shear strength of 16 ± 3 MPa is obtained for the joint prepared at 900°C for 30 min. The plastic deformation of the Ag–Pd interlayer and pullout of fibers inside ceramic contributed to the superior performance. Nevertheless, as the holding time and temperature reached 90 min and 950°C, the high chemical affinity of the Pd–Si system and enhanced atomic diffusion led to the massive formation of Pd2Si, which increased the joint brittleness and degraded the ceramic performance.

High–performance protonic ceramic fuel cells with a PrBa0.5Sr0.5Co1.5Fe0.5O5+δ cathode with palladium–rich interface coating

This study reports on protonic ceramic fuel cells (PCFCs) that exhibit enhanced performance after the addition of palladium (Pd) interlayers at the cathode–electrode interface. The Pd interlayer is deposited by sputtering on the BaZr0.2Ce0.6Y0.1Yb0.1O3-δ (BZCYYb) electrolyte surface, followed by the inkjet printing of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) and sintering. The proposed method successfully has produced a Pd layer that was well integrated between the BZCYYb and PBSCF layers, with no undesired reactions or phase formation. The Pd layer is diffused along the inner surface of the porous PBSCF cathode with the desired gradient composition. In our experiment, the fuel cell power is enhanced by up to 60% compared to the untreated PCFCs. In the former, the peak power density of the optimal cell is 420 mW cm−2, while that of the untreated sample is 260 mW cm−2 at 500 °C. The long-term stability of the Pd interlayer is confirmed during cell operation. The impedance analysis has revealed that the presence of the Pd significantly enhances the current collection and reduces the polarization impedance at the cathode–electrolyte interface, especially at low temperatures. These results indicate that the proposed method is promising for the fabrication of high-performance and robust PCFCs.

Debonding simulation of Fe-Ni interface with Pd interlayer and strength evaluation by atomic elastic stiffness coefficient

Debonding simulation of Fe-Ni interface with Pd interlayer and strength evaluation by atomic elastic stiffness coefficient

Effect of Pd Buffer and Interlayer on the Magnetic Properties of CoCrPt-Oxide Granular Thin Films

Morphostructural and magnetic properties of CoCrPt-oxide (TiO2, CoO) granular thin films deposited on Pd( $y$ )/Ru/Pd( $x$ )/NiTa intermediate layer have been investigated as a function of the Pd thickness ( $x = 5$ and 10 nm; $y = 1, 3$ , and 5 nm). The Pd( $x$ ) buffer layer shows an fcc (111) texture that leads to a gradual improvement of both the Ru and CoCrPt hcp (0002) crystallographic orientations while increasing the Pd thickness. This results on a significant enhancement of both the effective magnetic anisotropy ( ${K} _{\mathrm {eff}} =4.1 \times 10^{6}$ erg/cm3) and out-of-plane coercivity ( ${H} _{c\bot } = 5.7$ kOe) with respect to the reference CoCrPt-oxides/Ru/NiTa sample ( $K_{\mathrm {eff}} = 3.4 \times 10^{6}$ erg/cm3, ${H} _{c\bot }= 4.7$ kOe) when a 10 nm-thick Pd buffer is used. The inclusion of a Pd( $y$ ) intermediate layer between Ru and Co leads to an increase of the effective anisotropy (up to $4.1 \times 10^{6}$ erg/cm3 for $y = 5$ nm) with respect to the reference sample, which can be ascribed to a combined effect of an interface contribution and a term arising from a CoCrPt lattice distortion.

Multimetallic AuPd@Pd@Pt core-interlayer-shell icosahedral electrocatalysts for highly efficient oxygen reduction reaction

Incorporating Pt with core metals into Pt-based core-shell catalysts is regarded as a promising strategy to substantially enhance the catalytic properties towards oxygen reduction reaction (ORR) in fuel cells due to the synergetic effect between distinct metals. In this wok, ultrathin Pt skins with two atomic layers were epitaxially coated on as-prepared icosahedral Au50Pd50, Au60Pd40 and Au66Pd34 nanocrystal seeds, which are constructed with alloyed cores and Pd shells with different thickness. Through electron microscopic characterizations, Pd interlayers with tunable thickness of 3, 6, and 12 atomic layers can be found in the Au66Pd34@Pt, Au60Pd40@Pt and Au50Pd50@Pt icosahedra, respectively. These icosahedral AuPd@Pd@Pt nanocrystals show substantially enhanced activities and durabilities in electrocatalytic measurements towards ORR compared to Au75Pd25@Pt icosahedra without Pd interlayer and commercial Pt/C catalysts. Specifically, Au60Pd40@Pt icosahedra with 6 atomically thick Pd interlayer display the best electrocatalytic performances, whose mass activities before and after durability tests of 50,000 cycles are 11.6 and 30.2 times, respectively, as high as that of the commercial Pt/C.

Tuning the perpendicular magnetic anisotropy, spin Hall switching current density, and domain wall velocity by submonolayer insertion in Ta/CoFeB/MgO heterostructures

By submonolayer insertion of Au, Pt, or Pd into Ta/CoFeB/MgO/Ta heterostructures, we tune the perpendicular magnetic anisotropy and the coercive field of the ferromagnetic layer. We demonstrate that this has a major influence on the spin Hall switching current density and its dependence on the external magnetic field. Despite a rather small effective spin Hall angle of θSH≈−0.07, we obtain switching current densities as low as 2×1010 A/m2 with a 2 Å Au interlayer. We find that the Dzyaloshinskii-Moriya interaction parameter D is reduced with Au or Pd interlayers, and the perpendicular anisotropy field is reduced by an order of magnitude with the Pd interlayer. The dependence of the switching current density on the current pulse width is quantitatively explained with a domain wall nucleation and propagation model. Interface engineering is thus found to be a suitable route to tailor the current-induced magnetization switching properties of magnetic heterostructures.

Mechanical characterization of electrochemically based W – Cu joints for low-temperature heat sink application

Joining of the armor material tungsten to other alloys and especially to copper components which will act as heat sinks in divertor application is rather challenging due to the missing miscibility of tungsten and copper. This metallurgical behavior avoids the direct processing of W – Cu joints with sufficient mechanical stability. Introducing adapted interlayers can overcome these limitations if they exhibit extended miscibility with both partners to be joined.Electrochemical plating was chosen as deposition technology for such reactive interlayers and demonstrators were processed with a 10μm thick reactive Pd interlayer and joined by diffusion bonding. Their metallurgical behavior was characterized in dependence on processing temperature, reaction time and applied pressing load. The fabricated joints were mechanically qualified by shear testing. Cracking of the joints never appeared at the boundary of interlayer to W. The demonstrators revealed reasonable and applicable shear strength of around 100MPa. The observed shear strength values and formed microstructures in the joining zone will be displayed and discussed in dependence on the applied processing parameters. The developed bonding process by applying electrochemically plated interlayers has proven to be a reliable tool with industrial application potential.

Anomalous Enhancement of the Magnetic Anisotropy of CoCrPt Alloy Thin Film With Ultrathin Pt Interface

An anomalous enhancement of the coercive field ( $H_{c}$ ) and of the perpendicular magnetic anisotropy (PMA) of CoCr10Pt10 (at.%) alloy thin films is observed when the magnetic layer is deposited on an ultrathin Pt interlayer (IL). The dc magnetic properties of Pt/CoCr10Pt10 are studied as a function of the magnetic alloy thickness (4–8 nm) and the Pt IL thickness (up to 3 nm). Both the coercive field and the interface anisotropy ( $K_{s}$ ) exhibit a non-monotonic dependence on the Pt thickness, showing a characteristic peak value at an intermediate thickness, with a rise in the PMA up to 25%. Similar thickness dependence of $H_{c}$ is observed when using Pd and Ir ILs, but with a more moderate enhancement. This approach provides a means to control and engineer the PMA of CoCrPt alloys, and may find an application in data storage and low-power spinelectronics.

Proton Conducting Micro-Solid Oxide Fuel Cells with Nanoscale Palladium Interlayers

Thin film fuel cells with proton conducting oxide electrolytes have been fabricated and characterized. A comparison is made between fuel cells with and without Pd interlayers at the electrode-electrolyte interface. A nearly two-fold increase in power density was observed in the performance of a thin film BYZ fuel cell by the addition of a palladium interlayer. The studies contribute to engineering improvements in thin film fuel cells and in the future could be useful to understand proton conduction in complex oxides via nanoscale selective permeation layers.

Enhanced hydrogen storage properties of Pd/Ti/Mg/Ti multilayer films using the catalytic effects of Pd

Here, we report the microstructural and hydrogen storage properties of a 40-layer film of Pd (x nm)/Ti (40 nm)/Mg (360 nm)/Ti (40 nm) (x = 0, 5, 10, and 20) fabricated using an ultra-high vacuum DC magnetron sputtering system. The superior hydrogen uptake of the Pd/Ti/Mg/Ti films was 6.42 wt. % for x = 10 at 150 °C. The hydrogen absorption time is strongly dependent on the Pd film thickness (0–40 nm). As a result, the Pd/Ti/Mg/Ti multilayer film with the Pd interlayer can be attributed to offer the further diffusion channels and the controlled growth rate of hydride formation at the Pd/Ti/Mg interfaces, which provides an overall enhancement of the hydrogen storage properties.

Effect of short-term aging on interfacial and mechanical properties of yttria stabilized zirconia (YSZ)/stainless steel joints

Two types of Ag-based metallic interlayers, Ag–Cu–Pd and Ag–Cu–Ti, were used to join yttria-stabilized zirconia (YSZ) to stainless steel for solid oxide fuel cell (SOFC) applications. The joined samples were aged at 850 °C/100 h in air for evaluation of thermomechanical stability of the joints. The microstructure of the interlayers and the interfaces of YSZ/interlayers and steel/interlayers before and after aging were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) equipped with energy dispersive spectrometer (EDS). The evaluation of tensile and shear strengths and hermeticity indicated that the joints with Ag–Cu–Ti interlayers have better bonding strength and hermeticity than the joints with Ag–Cu–Pd interlayers.

Effect of Pd Interlayer on Electrochemical Properties of ENIG Surface Finish in 3.5 wt.% NaCl Solution

The corrosion resistance of a multilayered (NiP-Pd-Au) coating with various thicknesses of palladium (Pd) interlayer deposited on copper by an electroless method was investigated using electrochemical techniques including potentiodynamic polarization and electrochemical impedance spectroscopy. In addition, the surface finish was examined by x-ray diffraction analysis and scanning electron microscopy, and the contact angle of the liquid–solid interface was recorded. The corrosion resistance of the copper substrate was considerably improved by Pd interlayer addition. Increase of the thickness of the Pd interlayer enhanced the performance of the Cu-NiP-Pd-Au coating due to low porosity, high protective efficiency, high charge-transfer resistance, and contact angle. These are attributed to the diffusion of layers in the Cu-NiP-Pd-Au coating acting as a physical barrier layer, leading to the protection provided by the coating.

Hydrogen-induced enhancement of atomic diffusion in electrodeposited Pd films

Abstract The hydrogen-induced enhancement of atomic diffusion in electrodeposited Pd films on Cu substrate has been investigated with thermal desorption spectroscopy, X-ray diffraction, and transmission electron microscopy. The hydrogen content in Pd films ( x = H/Pd) was 2.2–7.7 × 10 −2 and decreased with time at room temperature. For Pd films with lower hydrogen contents ( x ≦ 4.0 × 10 −2 ), lattice contraction and grain growth proceeded as hydrogen desorption proceeded. For Pd films with higher hydrogen contents ( x ≧ 5.8 × 10 −2 ), fine grains became large columnar grains, and a large-grained Cu–Pd interlayer was formed by interdiffusion between the Cu substrate and the Pd film.

Interfacial characterization of YSZ-to-steel joints with Ag–Cu–Pd interlayers for solid oxide fuel cell applications

Yttria-stabilized zirconia (YSZ)/stainless steel joints made using two commercial silver-based interlayers containing palladium (58Ag–32Cu–10Pd and 65Ag–20Cu–15Pd), were systematically analyzed for the microstructures of the interlayer matrices, interlayer–steel interface, and interlayer–YSZ interface using scanning electron microscopy (SEM) and transmission electron microscopy coupled with energy dispersive spectroscopy (TEM/EDS). In the interlayer matrix, a face-centered cubic (FCC) Cu-rich phase formed in the vicinity of the YSZ and dissolved a significant amount of Zr from the ZrO2 and minor amounts of Fe and Cr from the steel. The Cu-rich phase in the interlayer matrix in the vicinity of the steel substrate was the ordered phase Cu3Pd with antiphase boundaries (APBs) and the L12 crystal structure. Silver particles precipitated within the Cu3Pd phase in 58Ag–32Cu–10Pd; a Fe(Cr) needle-like phase, instead of Ag particles, precipitated within the Cu3Pd phase in 65Ag–20Cu–15Pd. Although no reaction products at the interlayer–steel interface were found, dislocations appeared within the Ag- and Cu-rich phases. At the interlayer–YSZ interface, two reaction products, SiO2 (impurity in YSZ) and Ti3O5 (from the reaction of YSZ with Ti impurities in the steel) were observed. Diffusion and chemical reactions led to the compositional changes and interface reconstruction, thereby yielding metallurgically sound YSZ/steel joints.

Improving the thermal stability of nickel monosilicide thin films by combining annealing with the use of an interlayer and a capping layer

The authors investigated the effects of preannealing a 2-nm-thick Pd interlayer and a 20-nm-thick TiN capping layer on the electrical and thermal stability of nickel silicides as a function of the annealing temperature. The preannealed samples (prepoly-Si) produce lower sheet resistances compared to the samples without preannealing. For the preannealed samples, NiSi remains stable up to 600 °C. Transmission electron microscopy results show that the preannealed samples have a higher resistance against layer inversion. The addition of a Pd interlayer at the Ni film/prepoly-Si interface increases the formation temperature of NiSi2 to 900 °C. The use of the capping layer on the Pd-interlayered prepoly-Si samples improves the electrical and morphological stabilities of NiSi. The possible mechanisms for the preannealing and interlayer-induced improvement of the thermal stabilities of the Ni-silicide samples are discussed in terms of grain growth and simple thermodynamic relations.

High-Density Bit Patterned Media: Magnetic Design and Recording Performance

We examine the magnetic properties and recording performance of bit patterned exchange coupled composite (ECC) magnetic media at different bit and island aspect ratios. The ECC media consists of Co/Pd and Co/Ni multilayers whose coupling is controlled using Pd interlayers. We show that this multilayer system can be tuned to provide writeable media with a low switching field distribution for bit patterned magnetic recording. The recording performance of 100 Gb/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> media shows a sub 1e-4 bit error rate floor and misregistration errors that are well-described by a simple error model.

Characterization of graphene-based supercapacitors fabricated on Al foils using Au or Pd thin films as interlayers

We demonstrate that an Au or Pd interlayer between graphene and an Al-foil current collector plays an important role in enhancing supercapacitor performance. Graphene was prepared by scalable chemical exfoliation and mild thermal reduction (∼150 °C) processes. Working electrodes were prepared by coating the graphene on Au/Al or Pd/Al by drop-dry method. The graphene deposited on the noble metals Au and Pd demonstrated excellent supercapacitor performance. Estimated specific energy and specific power of supercapacitors were ∼40 Wh/kg and ∼40 kW/kg at the current density of ∼33 A/g, when operated in organic solution. Altogether, we demonstrate that employing noble metals in the fabrication of graphene-based supercapacitors can lead to excellent performance, and this could be a critical basis for further development of graphene-based supercapacitors.