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Predith, Ashley; Ceder, Gerbrand; Wolverton, Christopher; Persson, Kristin A.; Mueller, Tim

doi:10.1103/physrevb.77.144104

Cited by 81 publications

(55 citation statements)

References 54 publications

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“…First principles calculations are ideally suited to study coherent phase stability in the IV-VI rocksalt alloys. Density functional theory (DFT) calculations have been applied to phase stability problems in metallic alloys, [23][24][25][26][27][28][29][30][31][32][33] semiconductor alloys, [34][35][36][37][38][39][40][41] and oxide systems [42][43][44][45][46][47] with great success. Lead chalcogenide compounds and alloys have also been studied extensively with DFT, focusing mostly on either the electronic structure [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] or lattice dynamics 41,[63][64][65][66][67][68][69] o...…”

Section: Fig 1 (Color Online) Schematic Phase Diagram Of a Pseudo-bmentioning

confidence: 99%

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

Doak

Wolverton

2012

Phys. Rev. B

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Nanostructures formed by phase separation improve the thermoelectric figure of merit in lead chalcogenide semiconductor alloys, with coherent nanostructures giving larger improvements than incoherent nanostructures. However, large coherency strains in these alloys drastically alter the thermodynamics of phase stability. Incoherent phase stability can be easily inferred from an equilibrium phase diagram, but coherent phase stability is more difficult to assess experimentally. Therefore, we use density functional theory calculations to investigate the coherent and incoherent phase stability of the IV-VI rocksalt semiconductor alloy systems Pb(S,Te), Pb(Te,Se), Pb(Se,S), (Pb,Sn)Te, (Sn,Ge)Te, and (Ge,Pb)Te. Here we use the term coherent to indicate that there is a common and unbroken lattice between the phases under consideration, and we use the term incoherent to indicate that the lattices of coexisting phases are unconstrained and allowed to take on equilibrium volumes. We find that the thermodynamic ground state of all of the IV-VI pseudo-binary systems studied is incoherent phase separation. We also find that the coherency strain energy, previously neglected in studies of these IV-VI alloys, is lowest along 111 (in contrast to most fcc metals), and is a large fraction of the thermodynamic driving force for incoherent phase separation in all systems. The driving force for coherent phase separation is significantly reduced, and we find that coherent nanostructures can only form at low temperatures where kinetics may prohibit their precipitation. Furthermore, by calculating the energies of ordered structures for these systems we find that the coherent phase stability of most IV-VI systems favors ordering over spinodal decomposition. Our results suggest that experimental reports of spinodal decomposition in the IV-VI rocksalt alloys should be re-examined. PACS number(s): 64.75. Nx, 82.60.Nh, 84.60.Rb, 64.70.kg 2

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Section: Fig 1 (Color Online) Schematic Phase Diagram Of a Pseudo-bmentioning

confidence: 99%

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

Doak

Wolverton

2012

Phys. Rev. B

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“…One prototypical application for approximate energy models is the prediction of ordered ground states based on an underlying lattice topology. 12,13 The concept of CEs goes back to the Ising model, 14 which describes the magnetic phases of an atomic lattice in terms of pair interactions. A CE model, or generalized Ising model, is the discrete sum representation of materials properties in terms of lattice site topologies and site interactions, such as site pairs, triplets, quadruplets, and so on.…”

Section: Introductionmentioning

confidence: 99%

Construction of ground-state preserving sparse lattice models for predictive materials simulations

et al. 2017

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First-principles based cluster expansion models are the dominant approach in ab initio thermodynamics of crystalline mixtures enabling the prediction of phase diagrams and novel ground states. However, despite recent advances, the construction of accurate models still requires a careful and time-consuming manual parameter tuning process for ground-state preservation, since this property is not guaranteed by default. In this paper, we present a systematic and mathematically sound method to obtain cluster expansion models that are guaranteed to preserve the ground states of their reference data. The method builds on the recently introduced compressive sensing paradigm for cluster expansion and employs quadratic programming to impose constraints on the model parameters. The robustness of our methodology is illustrated for two lithium transition metal oxides with relevance for Li-ion battery cathodes, i.e., Li 2x Fe 2(1−x) O 2 and Li 2x Ti 2(1−x) O 2 , for which the construction of cluster expansion models with compressive sensing alone has proven to be challenging. We demonstrate that our method not only guarantees ground-state preservation on the set of reference structures used for the model construction, but also show that out-of-sample ground-state preservation up to relatively large supercell size is achievable through a rapidly converging iterative refinement. This method provides a general tool for building robust, compressed and constrained physical models with predictive power. 1, 2, 5 Although implementations with increasing numerical efficiency and growing computational power have made it possible to simulate ever larger structures with DFT, the method's intrinsic scaling with the number of electrons prevents applications that require large structures (thousands of atoms) and intensive sampling (millions of configurations). Approximate energy models fitted to DFT reference data, such as cluster expansion (CE) lattice models 6-9 or machine learning regression, 10, 11 can overcome these limitations by constructing computationally more efficient models with accuracies that are close to DFT for a chosen structural and chemical space. One prototypical application for approximate energy models is the prediction of ordered ground states based on an underlying lattice topology.

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“…Previously, CE methods have been successfully used in calculating alloy phase diagrams, 6 predicting new material ground states, 7 exploring diffusion mechanisms in Li intercalated systems, 8,9 and discerning the composition of ceria interfaces. 10 In this work, CE methods are applied to YSZ to gain distinct insight into dopant/ vacancy ordering properties.…”

Section: Introductionmentioning

confidence: 99%

First-principles thermodynamic modeling of atomic ordering in yttria-stabilized zirconia

2010

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Yttria-stabilized zirconia ͑YSZ͒ is modeled using a cluster expansion statistical thermodynamics method built upon a density-functional theory database. The reliability of cluster expansions in predicting atomic ordering is explored by comparing with the extensive experimental database. The cluster expansion of YSZ is utilized in lattice Monte Carlo simulations to compute the ordering of dopant and oxygen vacancies as a function of concentration. Cation dopants show a strong tendency to aggregate and vacate significantly sized domains below 9 mol % Y 2 O 3 , which is likely important for YSZ aging processes in ionic conductivity. Evolution of vibrational and underlying electronic properties as a function of Y doping is explored.

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Ab initioprediction of ordered ground-state structures inZrO2-Y2O3

Cited by 81 publications

References 54 publications

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

Construction of ground-state preserving sparse lattice models for predictive materials simulations

First-principles thermodynamic modeling of atomic ordering in yttria-stabilized zirconia

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