Sergey Barabash

First-principles theory of competing order types, phase separation, and phonon spectra in thermoelectric AgPbmSbTem+2 alloys

Using a first-principles cluster expansion, we shed light on the solid-state phase diagram and structure of the recently discovered high-performance Pb-Ag-Sb-Te thermoelectrics. The calculated bulk thermodynamics favors the formation of coherent precipitates of ordered Ag m Sb n Te m+n phases immiscible with rocksalt PbTe, such as AgSbTe 2 . The solubility is high for Pb in AgSbTe 2 and low for (Ag,Sb) in PbTe (8% vs 0.6% at 850 K). The differences in the phonon spectra of PbTe and AgSbTe 2 suggest that these precipitates enhance the thermoelectric performance by lowering thermal conductivity.

First-principles study of phase stability of Gd-doped EuO and EuS

TheoxidesystemhasawidemiscibilitygapontheGd-richsidebutformsorderedcompoundsontheEu-richside, exhibiting a deep asymmetric convex hull in the formation enthalpy diagram. The sulfide system has no stable compounds. The large difference in the formation enthalpies of the oxide and sulfide compounds is attributed to the contribution of local lattice relaxation, which is sensitive to the anion size. The solubility of Gd in both EuO and EuS is in the range of 10%‐20% at room temperature and quickly increases at higher temperatures, indicating that highly doped disordered solid solutions can be produced without the precipitation of secondary phases. We also predict that rocksalt GdO can be stabilized under appropriate experimental conditions.

Phase stability, ordering tendencies, and magnetism in single-phase fcc Au-Fe nanoalloys

Bulk Au-Fe alloys separate into Au-based fcc and Fe-based bcc phases, but L1

Materials screening workflow methodologies for metal oxides and chalcogenides for use in novel devices

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Magnetism without magnetic ions: percolation, exchange, and formation energies of magnetism-promoting intrinsic defects in CaO.

and L1

Nonstoichiometry as a source of magnetism in otherwise nonmagnetic oxides: Magnetically interacting cation vacancies and their percolation

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Prediction of unusual stable ordered structures of Au-Pd alloys via a first-principles cluster expansion

orderings were reported in single-phase Au-Fe nanoparticles. Motivated by these observations, we study the structural and ordering energetics in this alloy by combining density functional theory (DFT) calculations with effective Hamiltonian techniques: a cluster expansion with structural filters, and the configuration-dependent lattice deformation model. The phase separation tendency in Au-Fe persists even if the fcc-bcc decomposition is suppressed. The relative stability of disordered bcc and fcc phases observed in nanoparticles is reproduced, but the fully ordered L1

First-Principles Combinatorial Design of Transition Temperatures in Multicomponent Systems: The Case of Mn in GaAs

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First-principles determination of low-temperature order and ground states of Fe-Ni, Fe-Pd, and Fe-Pt

AuFe, L1

First-principles theory of the coherency strain, defect energetics, and solvus boundaries in the PbTe-AgSbTe 2 system

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