Revisiting the CuPt3 prototype and the L13 structure

Chumani Mshumi, Candace I. Lang, Lauren R. Richey, K. C. Erb, Conrad W. Rosenbrock, Lance J. Nelson, Richard R. Vanfleet, Harold T. Stokes, Branton J. Campbell, Gus L W Hart*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Experimentally and computationally, the structure of Pt-Cu at 1:3 stoichiometry has a convoluted history. The L13 structure has been predicted to occur in binary alloy systems, but has not been linked to experimental observations. Using a combination of electron diffraction, synchrotron X-ray powder diffraction, and Monte Carlo simulations, we demonstrate that it is present in the Cu-Pt system at 1:3 stoichiometry. We also find that the 4-atom, fcc superstructure L13 is equivalent to the large 32-atom orthorhombic superstructure reported in older literature, resolving much of the confusion surrounding this composition. Quantitative Rietveld analysis of the X-ray data and qualitative trends in the electron-diffraction patterns reveal that the secondary X1+(a,0,0) order parameter of the L13 phase is unexpectedly weak relative to the primary L1+(a,a,0,0) order parameter, resulting in a partially-ordered L1 3 ordering, which we conclude to be the result of kinetic limitations. Monte Carlo simulations confirm the formation of a large cubic superstructure at high temperatures, and its eventual transformation to the L13 structure at lower temperature, but also provide evidence of other transitional orderings.

Original languageEnglish
Pages (from-to)326-336
Number of pages11
JournalActa Materialia
Volume73
DOIs
Publication statusPublished - Jul 2014

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