Verifying predictions of theL13crystal structure in Cd-Pt and Pd-Pt by exhaustive enumeration

Abstract

͑2001͔͒ predicted a never-before-observed crystal structure in Ag-Pd. Recently, Curtarolo predicted the same structure to be stable in Pt-Cd and Pt-Pd ͓S. Curtarolo et al., CALPHAD: Comput. Coupling Phase Diagrams Thermochem. 29, 163 ͑2005͔͒. The predicted structure is unique in several ways. Though never seen in any other face-centered-cubic-based intermetallic binary compound or ordered alloy, it is relatively simple-it contains only four atoms per unit cell. Furthermore, the structure is the only one of this small size, except the L1 2 structure, that cannot be characterized as a simple stacking of layers where each layer contains only one kind of atom. We construct a first-principlesbased Hamiltonian and search it for the thermodynamically stable ͑lowest energy͒ structures. Using a ͑practi-cally͒ exhaustive enumeration of about three million of the most likely candidate structures, we find that this new structure, designated L1 3 , is indeed a ground state in both Cd-Pt and Pd-Pt. Experimental efforts to validate the predictions are underway.

A high-throughput ab initio review of platinum-group alloy systems

“…For example, the prototype Pd 3 Ti 2 , reported only in the Pd-Ti system [36], also emerges as a calculated groundstate in the closely related systems Hf-Pd and Pt-Ti. In Hf-Pt, it appears as marginally stable, at 3meV/atom above the convex hull, in agreement with a very recent experimental study that identified the previously incorrectly character- [2,13,25,27,29,31]. ∆H are the formation enthalpies from the present study.…”

“…Indeed many recent studies present such calculations of PGM alloy structures . However, most of these studies consider a limited * E-mail address: stefano@duke.edu number of structures, at just a few stoichiometries of a single binary system or a few systems [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Some cluster expansion studies of specific binary systems include a larger set of structures, but limited to a single lattice type (usually, fcc) [18][19][20][21][22][23].…”

Computational Materials Discovery Goes Platinum

“…We also find a few other compounds with unobserved prototypes (marked by a ? in Tables I, II, III, IV, V, and VI) previously uncovered in related HT studies [2,13,25,27,29,31].…”

“…In addition, the reader can prepare phase diagrams (as in Figs. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] linked to the appropriate structure URL locations. The Supplemental Material contains the whole set of geometrical and relaxed structures with ab initio total energies and formation enthalpies (see Ref.…”

“…Indeed, many recent studies present such calculations of PGM alloy structures . However, most of these studies consider a limited number of structures, at just a few stoichiometries of a single binary system or a few systems [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Some cluster expansion studies of specific binary systems include a larger set of structures, but limited to a single lattice type (usually fcc) [18][19][20][21][22][23].…”