Thermodynamics and nonstoichiometry in the intermetallic compound Pt 3 In

“…Similar experiments were performed for Pt 3 Ga [39] and Pt 3 In [40], and the defect formation energies were determined by a corresponding statistical-thermodynamic evaluation of the obtained activity values. Table 2 lists the defect formation energies of all L1 2 compounds investigated in our laboratory.…”

Section: Application Of the L1 2 Model To Ni 3 Ga Pt 3 Ga And Pt 3 Inmentioning

confidence: 99%

A3B Intermetallics: Defect chemistry and nonstoichiometry

Ipser

2007

Pure and Applied Chemistry

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Abstract:The defect chemistry of different ordered intermetallic compounds with the A 3 B stoichiometry was investigated. Three groups were distinguished according to their crystal structure: L1 2 compounds (Ni 3 Al, Ni 3 Ga, Pt 3 Ga, Pt 3 In), D0 19 compounds (Ti 3 Al), and D0 3 compounds (Fe 3 Al, Ni 3 Sb). Statistical-thermodynamic models were derived based on a Wagner-Schottky approach, and the calculated activity curves (thermodynamic activity vs. composition) were compared with experimental activity data. In this way, we attempted to obtain at least estimated values for the energies of formation of the different types of point defects present in the corresponding compound, both as configurational defects (which are responsible for nonstoichiometry) and as thermal defects. In the majority of cases, thermodynamic activities had to be determined experimentally in the present study, using either an emf method with a solid electrolyte (Ni 3 Ga, Pt 3 Ga, Pt 3 In, Fe 3 Al) or a Knudsen cell-mass spectrometric method (Ni 3 Sb).

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“…In this part, we show some of the principles which were used for the modeling of a defect structure in intermetallics with B2‐, and L1 2 ‐structures39, 70, 71, 76–78, 81–88 applying a Wagner–Schottky Approach 81. The Wagner–Schottky Approximation works under the assumption that (at constant pressure) the internal energy, volume, and vibrational entropy of the crystal are linear functions of the number of atoms or vacancies, respectively, in the different sublattices 39.…”

Section: Application Of the Wagner–schottky Mean‐field Approachmentioning

confidence: 99%

“…The modeling approach selected here uses the energies of formation of the different point defects as adjusted parameters,32, 70, 71, 76, 77, 81–88 although, of course, some disorder or long range order parameter could be used equally well 39. The advantage of using the energy parameters in the present case lies in the possibility to test the values that are available in the literature.…”

Section: Application Of the Wagner–schottky Mean‐field Approachmentioning

confidence: 99%

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A Statistical‐Thermodynamic Modeling of Ordering Phenomena in Binary Intermetallic B2‐ and L1₂‐Structures

Semenova

Krachler

2012

Adv Eng Mater

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Statistical‐thermodynamic models for the description of ordering in non‐stoichiometric intermetallic phases can be very helpful for the design of new functional materials for various purposes. Here, we present a review of methods for describing B2 (BCC) and L12 (FCC) – type binary alloys. The free energy of binary alloys where ordered structures are formed, is evaluated by statistical approaches employing applications of the Bragg–Williams–Gorsky mean‐field approximation. In the original mean field method, the degree of order in the neighborhood of a given site in the crystal is determined by the average state of order throughout the macroscopic crystal. Actually, the force tending to produce long‐range order depends on the fluctuations in the configuration, an effect which is neglected in the mean field approximation but is taken under consideration, e.g., in the Quasi‐Chemical Approach (QCA) by Guggenheim and its advanced applications, in various sophisticated treatments using the Cluster Variation Method (CVM) originally developed by Kikuchi, as well as in the Defect Correlation Model (DCM). The latter model is a less sophisticated method based on the simultaneous description of short‐range order and long‐range order by use of properly defined non‐overlapping clusters. All these methods allow the “pure” mean‐field results to be substantially refined, particularly at high temperatures, and for alloys with large deviations from the stoichiometric composition. Defect concentration‐alloy composition diagrams and activity‐alloy composition diagrams are shown for several methods with focus on the QCA and DCM approaches. The calculated results are compared with each other and with experimental data on thermodynamic and structural properties from the literature.

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Thermodynamics and nonstoichiometry in the intermetallic compound Pt 3 In

Cited by 6 publications

References 17 publications

A thermodynamic study of the D03-ordered intermetallic compound Fe3Al

A thermodynamic study of the D03-ordered intermetallic compound Fe3Al

A3B Intermetallics: Defect chemistry and nonstoichiometry

A Statistical‐Thermodynamic Modeling of Ordering Phenomena in Binary Intermetallic B2‐ and L1₂‐Structures

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Thermodynamics and nonstoichiometry in the intermetallic compound Pt 3 In

Cited by 6 publications

References 17 publications

A thermodynamic study of the D03-ordered intermetallic compound Fe3Al

A thermodynamic study of the D03-ordered intermetallic compound Fe3Al

A3B Intermetallics: Defect chemistry and nonstoichiometry

A Statistical‐Thermodynamic Modeling of Ordering Phenomena in Binary Intermetallic B2‐ and L12‐Structures

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A Statistical‐Thermodynamic Modeling of Ordering Phenomena in Binary Intermetallic B2‐ and L1₂‐Structures