Pd Sn System Research Articles

Experimental investigation of Ag–Pd–Sn ternary system

Isothermal sections of the Ag–Pd–Sn system at 500 and 800 °C were plotted based on the XRD and EDX results. The solubility of Sn in palladium and silver-based fcc solid solution has nearly zero minimum around the Ag corner. The Pd3Sn and γ-Pd2–xSn phases show significant dissolution of Ag and extend towards the Ag corner. The other Pd–Sn and Ag–Sn binary phases dissolve under 5 at.% of the third component. A new τ1 ternary phase was discovered in the Pd-rich region. Its XRD pattern corresponds formally to In structure type, but the actual arrangement of the atoms in the τ1 phase most probably corresponds to tetragonal Al3Ti type structure.

Phase Equilibria of the In–Pd–Sn System at 500 °C and 800 °C: Experimental Study and CALPHAD Modeling

Phase equilibria in the In-Pd-Sn system were investigated by a combination of key experiments and thermodynamic modeling. Partial isothermal sections at 500 °C and 800 °C of the In-Pd-Sn system for Pd contents above 66 at.% have been plotted experimentally using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD). The solubility of the third component in binary compounds InPd3 and Pd3Sn was determined. The new ternary compound τ1 was found in Pd contents ranging from 20 to 25 at.% and at Sn contents varying from 5 to approximately 17 at.% Sn. This compound crystallizes in an Al3Ti-type tetragonal structure. Isostructural InPd2 and Pd2Sn phases from the In-Pd and Pd-Sn binary compositions form a continuous phase field in the ternary system at both temperatures. The temperatures of the solidus, liquidus, and phase transitions of the alloys along the Pd-In50Sn50 line were measured using DTA/DSC. Thermodynamic calculation of the In-Pd-Sn ternary system is performed using the CALPHAD method using the Thermo-Calc® software. The thermodynamic properties of the disordered fcc and liquid phases were described by the Redlich-Kister-Muggianu model. To describe intermetallic phases, namely, InPd3, Pd3Sn, τ1 and Pd2(InxSn1-x), a two-sublattice models was used. Thermodynamic description of the In-Pd-Sn system obtained in this study is in good agreement both with our results and the published experimental data.

Critical evaluation and thermodynamic modeling of the Pd–Sn system

The single crystalline material PdSn4, a homologue of the Dirac nodal arc semimetal PtSn4, is a promising candidate to search for new topological states with fascinating quantum physical properties. In the present work, the thermochemistry and phase diagram information of the Pd–Sn system published in the literature was collected and critically reviewed, two thermodynamic reassessments of the Pd–Sn system were carried out in the frame of the CALPHAD approach to optimize the Gibbs free energy of each phase presented in the system. The liquid phase was described using respectively the Bragg-Williams random mixing model and the associate solution model. All the reliable thermodynamic property and phase equilibria data can be generally described using the presently obtained thermodynamic descriptions of the Pd–Sn system. Issues related to the further improvement of the thermodynamic descriptions of the Pd–Sn system are discussed.

Growth of phases in the solid-state from room temperature to an elevated temperature in the Pd–Sn and the Pt–Sn systems

The solid-state growth of the product phases in bulk and electroplated diffusion couples of the Pd–Sn and the Pt–Sn systems is reported at various temperatures, ranging from room temperature to 215 °C. The growth rate of the product phase in the Pt–Sn system is found to be much lower compared to the Pd–Sn system and the Au–Sn system also, which is currently used in the microelectronics industry. The time dependent experiments indicate that the growth rate in the Pd–Sn system is parabolic in nature, i.e., it is controlled by the diffusion rates of components through the product phases. However, the growth rate is linear and hence reaction-controlled in the Pt–Sn system, which indicates that the formation of the compound is the rate-limiting step rather than the diffusion rates of components. The PdSn4 phase covers almost whole interdiffusion zone in the Pd/Sn couple, while PtSn4 is the only phase found in the Pt/Sn couple. The marker experiments indicate that both PdSn4 and PtSn4 grow mainly by the diffusion of Sn, with negligible diffusion of Pd and Pt, respectively. Furthermore, the analysis considering the same crystal structure (i.e., oC20) of these phases along with the concept of sublattice diffusion mechanism indicates that the diffusion rates of both Pd and Pt are negligible via both the lattice and the grain boundaries.

Diffusion and growth mechanism of phases in the Pd-Sn system

Growth mechanism of phases and atomic mechanism of diffusion are discussed in the Pd-Sn system. The Kirkendall marker plane location indicates that the PdSn4 phase grows because of diffusion of Sn. Atomic arrangement in the crystal indicates that Sn can diffuse through its own sublattice but Pd cannot diffuse unless antisites are present. The negligible diffusion of Pd indicates the absence of Pd antisites. The activation energy value indicates that the contribution from grain boundary diffusion cannot be neglected although experiments were conducted in the homologous temperature range of 0.7–0.79.

Phase relationships at 600 °C of the Yb–Pd–Sn system from 25 to 100 at.% Yb

Phase equilibria in the Yb–Pd–Sn system at 600 °C were investigated in the range from 25 to 100 at.% Yb, employing scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) and X-ray diffraction (XRD). The existence of five intermetallic compounds (YbPdSn, Yb 2Pd 2Sn, YbPd 2Sn, YbPdSn 2, Yb 2Pd 3Sn 5) was confirmed and three novel ternary phases were found. A few phases reveal a certain homogeneity range. In particular, Pd/Sn solubilities were found for YbPd 2Sn and YbPd 3 compounds.

Thermodynamic description of the ternary Pd–Sn–Zn system

Abstract The thermodynamic properties of the liquid Pd–Sn–Zn ternary system were investigated, because the Sn–Zn alloy is a promising lead-free solder and Pd can be used as a substrate material. Using an appropriate galvanic cell, the partial free energies of Zn in liquid Pd–Sn–Zn alloys were determined as a function of concentration and temperature. Thermodynamic properties were obtained for 18 alloys. Their composition was situated on two cross-sections with the constant molar ratios of Pd: Sn = 1:3 and 1:9. The integral Gibbs free energy and the integral enthalpy for the ternary system at 1000 K were calculated by Gibbs–Duhem integration. For the liquid binary Pd–Sn system, some inconsistencies were found in previous CALPHAD results. Considering the latest experimental information, the interaction parameters of the liquid phase were reevaluated. The liquidus temperatures were also determined from EMF measurements.

Highlights of experimental thermodynamics in the field of nuclear fuel development

Results of basic thermodynamic studies are presented in the fields of oxide fuel pins and their alloys with fission products and of the neutron multiplier beryllium. Gibbs energy of formation measurements of solid phases using galvanic cells with CaF 2 electrolyte are exemplarily described for chromium carbides, URu 3 and URh 3. The calculation of the corresponding value of UPd 3 is demonstrated using the phase diagram of the U–Pd–Sn system. The phase behaviour of (U, Pu)O 2 in a steady-state temperature gradient between the solidus and the liquidus is explained. The O/(U + Pu) redistribution in a temperature gradient is measured which allows the calculation of the heat of transport of the oxygen vacancies. The obstacles for measurements of the enthalpies of transformation and melting of beryllium are commented, the temperatures are only 14 degrees apart from each other below melting at 1283 °C. The high enthalpy of transformation is interpreted by the compressed c/ a-axis ratio of the hcp modification.

Enthalpies of mixing of metallic systems relevant for lead-free soldering: Ag–Pd and Ag–Pd–Sn

The partial and integral enthalpies of mixing of binary liquid Ag–Pd alloys (with compositions up to about 55 at.% Pd) were determined at 1400 °C. A Calvet type microcalorimeter was used for the measurements employing a drop calorimetric technique. Additionally, eight sections in the Sn-rich corner of the ternary Ag–Pd–Sn system, which is relevant for lead-free soldering, were investigated at 900 °C. The ternary interaction parameters were fitted using the Redlich–Kister–Muggiano model for substitutional solutions. The isoenthalpy curves for Ag–Pd–Sn at 900 °C were constructed for the integral molar enthalpy of mixing.

Enthalpies of mixing of liquid alloys in the In–Pd–Sn system and the limiting binary systems

The partial and integral enthalpies of mixing of molten binary In–Pd (up to about 29 at.% Pd), In–Sn (entire compositional range) and Pd–Sn (up to about 53 at.% Pd) alloys were determined at 900 °C. A Calvet-type microcalorimeter was used for the measurements employing a drop calorimetric technique. Additionally, five sections in the ternary In–Pd–Sn system (compositions up to about 40 at.% Pd) were investigated at 900 °C. The ternary interaction parameters were fitted using the Redlich–Kister–Muggiano model for substitutional solutions. The isoenthalpy curves for In–Pd–Sn at 900 °C were constructed for the integral molar enthalpy of mixing. Furthermore, the experimental results in the ternary system were compared with calculated values obtained by employing different binary extrapolation models.

Vaporization behaviour and some thermodynamic properties of the Pd-In, Pd-Pb, Pd-Sn systems

In this study, the vaporization behaviour of solid Pd-rich phases in the Pd–Pb, Pd–In and Pd–Sn systems was investigated by Knudsen-effusion-cell coupled with mass-spectrometry. The Pb, Pd, In vapor pressures [no Sn(g) has been detected in the vapor of Pd-Sn system] were evaluated in the temperatures range 1190–1563 K from the ion intensities measured over two-phases regions. Thermodynamic quantities were derived from vapor pressure data. In particular, for the Pd–Sn binary, the intermediate phase Pd 7Sn 2, the existence of which has been recently proposed, has been studied here for the first time. Furthermore, preliminary thermochemical data are presented for the diatomic intermetallic molecules PdSn and PdPb, which have been for the first time identified in the vapors in equilibrium over liquid solutions of appropriate composition at higher temperatures (1935–2025 K).

Magnetic behavior of new CePdSn ternary compounds

Abstract We have prepared and measured the magnetic susceptibility of several new ternary compounds in the CePdSn system: CePd0.5Sn2, Ce8Pd24Sn, “Ce4Pd7Sn4” and the solid solution based on Ce2Pd2Sn. In CePd0.5Sn2, an effective magnetic moment of 2.60(3)μB is observed but no ordering is apparent above 4.2 K. Complete nickel substitution for Pd in Ce(Pd1−xNix)0.5Sn2 results in the known lower limit to the CeNi1−xSn2 solid solution. We have determined the extent of the solid solution based on Ce2Pd2Sn to have the form Ce4Pd4+2xSn2−x−y in a roughly triangular region with limits of x = 0, y = 0; x = 0, y ≈ 2 3 and x ≈ 2 3 , y = 0. Magnetic behavior consistent with trivalent cerium moments is observed at these limits with ferromagnetic ordering present for x = 0, y = 2 3 . Cubic Ce8Pd24Sn has an effective high temperature moment of 2.49(4)μB and antiferromagnetic ordering at 7.5 K. A hexagonal phase dominates the composition “Ce4Pd7Sn4”, but a structural solution has remained elusive. An effective cerium moment of 2.53(4)μB is observed in “Ce4Pd7Sn4” with a Weiss constant of −23 K, suggesting antiferromagnetic interactions, but no ordering is observed above 4.2 K.