First-principles study of constitutional and thermal point defects in B2 PdIn

Jiang, Chao; Chen, Lei; Liu, Zhe

doi:10.1016/j.intermet.2005.05.012

Cited by 9 publications

(4 citation statements)

References 36 publications

(49 reference statements)

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“…Our calculated equilibrium lattice parameters of bct indium and fcc palladium are 1%-2% larger than those deduced from experiments, while the one calculated within the local density approximation scheme are found to be 1%-2% smaller. 33 This is in agreement with the usual LDA over-binding and GGA over-corrections. Concerning bulk Pd, our PAW-PBE calculations are also in agreement with previously published all electron calculations, 32 justifying the use of time-saving pseudopotentials rather than all electron potentials.…”

Section: A Bulk Structures and Cohesive Energiessupporting

confidence: 85%

“…The constitutional point defects are identified to be Pd vacancies (In-rich alloys) and Pd antisites (Pd-rich alloys) by first principles calculations. 33 The presence of such defects can modify strongly the In segregation pattern. [47][48][49] To investigate the influence of the composition on surface segregation, we have compared the total energies of slabs containing one point defect either in surface or in "bulklike" layer (position S − 4).…”

Section: Indium Surface Segregation In Inpdmentioning

confidence: 99%

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Surface structures of In-Pd intermetallic compounds. II. A theoretical study

Gaudry

McGuirk

Ledieu

et al. 2014

The Journal of Chemical Physics

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The (110) surface of the InPd intermetallic compound and the In-Pd surface alloy properties are investigated in the framework of the density functional theory, within the projector augmented plane-wave method. Surface segregation is calculated to be energetically unfavorable at stoichiometric InPd(110) surfaces, while indium antisites are shown to segregate to the surface in off-stoichiometric InPd(110) systems. Concerning surface alloys obtained by burying In-doped Pd layers in Pd(111), we demonstrated that the most stable ones are those presenting atomic indium concentrations below 50 at. % (11 at. %, 25 at. %, 33 at. %). According to our calculations, the In-doped Pd layers with concentration above or equal to 50% lead to In-doped Pd multilayers, each presenting an atomic indium concentration below 50 at. %. Alloying and segregation effects in InPd intermetallic compound and In-Pd surface alloys clearly agree with the larger bonding strength of In-Pd (-0.44 eV) compared to In-In (-0.29 eV) and Pd-Pd (-0.31 eV).

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Section: A Bulk Structures and Cohesive Energiessupporting

confidence: 85%

Section: Indium Surface Segregation In Inpdmentioning

confidence: 99%

Surface structures of In-Pd intermetallic compounds. II. A theoretical study

Gaudry

McGuirk

Ledieu

et al. 2014

The Journal of Chemical Physics

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“…[141] Furthermore, our results suggest that the predominant thermal defects in B2 PdIn are of triple-Pd type and not of Schottky type. Unlike B2 NiAl, in which the thermal defects are of triple-defect type on the Ni-rich side and of interbranch type on the Al-rich side, [142] the thermal defects in B2 PdIn are of triple-defect type on both sides of stoichiometry.…”

Section: Defect Structure and Lattice Preferencementioning

confidence: 63%

First-Principles Calculations and CALPHAD Modeling of Thermodynamics

Liu

2009

J. Phase Equilib. Diffus.

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340

112

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Thermodynamics is the key component of materials science and engineering. The manifestation of thermodynamics is typically represented by phase diagrams, traditionally for binary and ternary systems. Consequently, the applications of thermodynamics have been rather limited in multicomponent engineering materials. Computational thermodynamics, based on the CALPHAD approach developed in the last few decades, has released the power of thermodynamics and enabled scientists and engineers to make phase stability calculations routinely for technologically important engineering materials. Within the similar time frame, first-principles quantum mechanics technique based on density functional theory has progressed significantly and demonstrated in many cases the accuracy of predicted thermodynamic properties comparable with experimental uncertainties. In this paper, the basics of the CALPHAD modeling and first-principles calculations are presented emphasizing current multiscale and multicomponent capability. Our research results on integrating first-principles calculations and the CALPHAD modeling are discussed with examples on enthalpy of formation at 0 K, thermodynamics at finite temperatures, enthalpy of mixing in binary and ternary substitutional solutions, defect structure and lattice preference, and structure of liquid, super-cooled liquid, and glass.

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“…The constitutional defects have been determined and are Pd vacancies for In-rich compositions and Pd antisites for Pdrich compositions. 49 Vacancy condensation at the surface might thus be an additional mechanism for the formation of the faceted holes. This implies a significant mobility in this temperature regime.…”

Section: Discussionmentioning

confidence: 99%

The atomic structure of low-index surfaces of the intermetallic compound InPd

McGuirk

Ledieu

Gaudry

et al. 2015

The Journal of Chemical Physics

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The intermetallic compound InPd (CsCl type of crystal structure with a broad compositional range) is considered as a candidate catalyst for the steam reforming of methanol. Single crystals of this phase have been grown to study the structure of its three low-index surfaces under ultra-high vacuum conditions, using low energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). During surface preparation, preferential sputtering leads to a depletion of In within the top few layers for all three surfaces. The near-surface regions remain slightly Pd-rich until annealing to ∼580 K. A transition occurs between 580 and 660 K where In segregates towards the surface and the near-surface regions become slightly In-rich above ∼660 K. This transition is accompanied by a sharpening of LEED patterns and formation of flat step-terrace morphology, as observed by STM. Several superstructures have been identified for the different surfaces associated with this process. Annealing to higher temperatures (≥750 K) leads to faceting via thermal etching as shown for the (110) surface, with a bulk In composition close to the In-rich limit of the existence domain of the cubic phase. The Pd-rich InPd(111) is found to be consistent with a Pd-terminated bulk truncation model as shown by dynamical LEED analysis while, after annealing at higher temperature, the In-rich InPd(111) is consistent with an In-terminated bulk truncation, in agreement with density functional theory (DFT) calculations of the relative surface energies. More complex surface structures are observed for the (100) surface. Additionally, individual grains of a polycrystalline sample are characterized by micro-spot XPS and LEED as well as low-energy electron microscopy. Results from both individual grains and "global" measurements are interpreted based on comparison to our single crystals findings, DFT calculations and previous literature.

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First-principles study of constitutional and thermal point defects in B2 PdIn

Cited by 9 publications

References 36 publications

Surface structures of In-Pd intermetallic compounds. II. A theoretical study

Surface structures of In-Pd intermetallic compounds. II. A theoretical study

First-Principles Calculations and CALPHAD Modeling of Thermodynamics

The atomic structure of low-index surfaces of the intermetallic compound InPd

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