Insight into Phase Stability in the Mg-Pd System: The Ab Initio Calculations

Abstract

Thermodynamic properties of all reported up to date intermetallic phases in Mg-Pd equilibrium system are reported in this work. Ab initio method was applied to calculate formation energies, relaxed lattice constants and bulk moduli. The consistent set of data was obtained, including formation energies and bulk moduli of Mg 6 Pd and Mg 9 Pd 11 that were calculated for the first time. The obtained energies of formation can be used for future thermodynamic optimization of promising hydrogen storage material Mg-Pd.

Calorimetric Studies of Magnesium-Rich Mg-Pd Alloys

“…This trend is observed to x Pd = 0.5, which is also documented by the Miedema model and ab initio calculations. Moreover, the obtained formation enthalpy of the alloy close to the composition of the Mg 6 Pd intermetallic phase is in very good agreement with the data measured by the direct reaction method [36], as well as the ab initio calculations [38]. A large discrepancy is observed between the values calculated using the Miedema model [45,46] and the experimental measurements, which reach~6 kJ/mol of atoms.…”

“…They were investigated using solution calorimetry in a liquid tin bath, and the determined formation energies equaled −27.0 ± 0.8, −34.4 ± 0.9, −35.2 ± 1.4, −44.2 ± 0.9, −46.0 ± 0.7, and −54.3 ± 2.3 kJ/mol of atoms for alloys containing 14.6 at.% Pd, 19.4 at.% Pd, 20.1 at.% Pd, 27.7 at.% Pd, 29.3 at.% Pd, and 35.5 at.% Pd, respectively. Moreover, the ab initio calculations of the formation energies of all existing intermetallic phases shown in Figure 1 were also reported in our other work [38].…”

“…The comparison of the formation enthalpies of the investigated alloys obtained in this study is presented in Figure 2 , together with the experimental data obtained from the direct reaction method [ 36 ], as well as the results from the ab initio method [ 34 , 38 ] and calculations using the Miedema model [ 45 , 46 ].…”

Mg3Pt2: Anionic Chains in a Eu3Ga2-Type Structure

“… 20 − 23 Besides their technological importance, exploring intermetallic compounds of Mg, their phase equilibria, and their structure–property relationships has been of general interest to the solid-state physics and chemistry community. 21 , 24 − 37 The high affinity of Mg to Pt metals 38 gives rise to a very variable structural chemistry, 39 , 40 as has been elaborated for the Mg–Rh, 41 − 46 Mg–Ir, 46 − 53 and several Mg–Pd 54 − 63 systems. For the Mg–Pt system, no phase diagram is reported in the literature; however, several intermetallic phases have already been described.…”

Insight into Phase Stability in the Mg-Pt System. The Ab Initio Calculations

“…According to Pearson, [14] the Mg 6 Pt intermetallic compound is isostructural with the Mg 6 Pd phase; therefore, it belongs to a group of quasicrystals. The modeling of its structure was done in the same manner as it was done in our previous work on Mg-Pd system [15] for Mg 6 Pd. First, the crystal positions of Mg and Pt atoms were taken from Samson [16] work, exchanging original Pd atoms into Pt atoms.…”