Ab initio study of low-temperature phase transformations in ternary solid solution TiCcN1−c

Vingurt, Dima; Fuks, David

doi:10.1016/j.intermet.2009.08.009

Cited by 7 publications

(2 citation statements)

References 33 publications

(43 reference statements)

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“…This approach was successfully applied earlier to similar complex perovskite materials including (Ba,Sr)TiO 3 (BST), 21 (La,Sr)MnO 3 (LSM), 22 (La,Sr)CoO 3 (LSC) 23 and also Ti x C 1Àx N alloys. 24 In order to predict the effect of the compositional variation of the multicomponent BSCF, we have constructed three phase diagrams (PDs) for the following solid solutions: Ba 1Àx Sr x CoO 3 (BSC), Ba 1Àx Sr x FeO 3 (BSF) (0 # x # 1) (A-type cations are mixed) and SrCo x Fe 1Àx O 3 (SCF) (0 # x # 1) (B-type cations are mixed). The changes in the morphology of solid solution with the chemical composition relevant for SOFC operation are analyzed in detail.…”

Section: Introductionmentioning

confidence: 99%

Ab initio thermodynamic study of (Ba,Sr)(Co,Fe)O3 perovskite solid solutions for fuel cell applications

et al. 2013

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Ba,Sr)(Co,Fe)O 3 (BSCF) perovskite solid solutions are promising materials for solid oxide fuel cell cathodes and oxygen permeation membranes. Cathode performance strongly depends on the morphology of these materials remaining as a single phase or two-phase mixture. Combining ab initio calculations of the atomic and electronic structure of different supercells with thermodynamics of solid solutions, we have constructed and discussed phase diagrams of several important BSCF chemical compositions. It is demonstrated that in BSC cobaltite solid solution the spinodal decomposition may occur already at relatively low temperatures, while ferrite (BSF and SCF) solid solutions decompose at relatively high temperatures forming a two-phase system where the coexisting hexagonal and cubic phases significantly differ in fractions of constituents.

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Section: Introductionmentioning

confidence: 99%

Ab initio thermodynamic study of (Ba,Sr)(Co,Fe)O3 perovskite solid solutions for fuel cell applications

et al. 2013

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“…Obviously, it is impossible to calculate all of the structures that may, in principle, exist in the solid solution. The possible routes to select the superstructures that should be examined for obtaining the energy parameters V ˜(0) and V ˜(k j s ) that determine the formation energy for the disordered solid solution and ordering energies for superstructures were described previously 21,29,38 where all the structures that are stable with respect to the formation of anti-phase domains were considered according to the criteria. 37 Further discussion on this subject was also made by Landau et al 39 In contradiction to that reported by Kirievsky et al, here only two ordered phases in the Pb-Ti sublattice of (Pb 1Àc Ti c )Te with the stoichiometric composition, c st = 0.5, are considered to estimate the solubility limit of Ti.…”

Section: Statistical Thermodynamics Approachmentioning

confidence: 99%

Combined electronic and thermodynamic approaches for enhancing the thermoelectric properties of Ti-doped PbTe

Komisarchik

Gelbstein

Fuks

2016

Phys. Chem. Chem. Phys.

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Lead telluride based compounds are of great interest due to their enhanced thermoelectric transport properties. Nevertheless, the donor type impurities in this class of materials are currently mainly limited and alternative types of donor impurities are still required for optimizing the thermoelectric performance. In the current research titanium as a donor impurity in PbTe is examined. Although titanium is known to form resonant levels above the conduction band in PbTe, it does not enhance the thermo-power beyond the classical predictions. Recent experiments showed that alloying with a small amount of Ti (∼0.1 at%) gives a significant increase in the figure of merit. In the current research ab initio calculations were applied in order to correlate the reported experimental results with a thermoelectric optimization model. It was found that a Ti concentration of ∼1.4 at% in the Pb sublattice is expected to maximize the thermoelectric power factor. Using a statistical thermodynamic approach and in agreement with the previously reported appearance of a secondary intermetallic phase, the actual Ti solubility limit in PbTe is found to be ∼0.3 at%. Based on the proposed model, the mechanism for the formation of the previously observed secondary phase is attributed to phase separation reactions, characterized by a positive enthalpy of formation in the system. With extrapolation of the obtained ab initio results, it is demonstrated that lower Ti-doping concentrations than previously experimentally reported ones are expected to provide power factor values close to the maximal one, making doping with Ti a promising opportunity for the generation of highly efficient n-type PbTe-based thermoelectric materials.

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Phase competition in (La_1 − c,Sr_c)CoO₃ solid solutions: ab initio thermodynamic study

Fuks

Weizman

Kotomin

2013

Physica Status Solidi (b)

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Statistical thermodynamics and density functional theory (DFT) formalisms are combined to analyze the phase competition of energetically preferable phases in (La1 − c,Src)CoO3 solid solutions upon LaCoO3 doping with Sr. La/Sr sublattice in ABO3 perovskite structure is considered as immersed in the field of CoO3 units and the superstructures that are stable with respect to the formation of antiphase domains are analyzed. The concentration‐dependent energy parameters determining the relative stability of the cubic superstructures (phases) are extracted. This allows us calculations of concentration‐ and temperature dependences of the long‐range order (LRO) parameters for different phases. The temperatures of the order–disorder phase transformations for energetically stable at T = 0 K phases are obtained. It is shown that the phase corresponding to the (La0.875,Sr0.125)CoO3 composition may exist at low temperatures. Nevertheless, already at room temperature it fails in the phase competition with the disordered (La1 − c,Src)CoO3 solid solution and the phase corresponding to the (La0.75,Sr0.25)CoO3 composition and thus hardly can be observed.

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Ab initio study of low-temperature phase transformations in ternary solid solution TiCcN1−c

Cited by 7 publications

References 33 publications

Ab initio thermodynamic study of (Ba,Sr)(Co,Fe)O3 perovskite solid solutions for fuel cell applications

Ab initio thermodynamic study of (Ba,Sr)(Co,Fe)O3 perovskite solid solutions for fuel cell applications

Combined electronic and thermodynamic approaches for enhancing the thermoelectric properties of Ti-doped PbTe

Phase competition in (La_1 − c,Sr_c)CoO₃ solid solutions: ab initio thermodynamic study

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Ab initio study of low-temperature phase transformations in ternary solid solution TiCcN1−c

Cited by 7 publications

References 33 publications

Ab initio thermodynamic study of (Ba,Sr)(Co,Fe)O3 perovskite solid solutions for fuel cell applications

Ab initio thermodynamic study of (Ba,Sr)(Co,Fe)O3 perovskite solid solutions for fuel cell applications

Combined electronic and thermodynamic approaches for enhancing the thermoelectric properties of Ti-doped PbTe

Phase competition in (La1 − c,Src)CoO3 solid solutions: ab initio thermodynamic study

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Phase competition in (La_1 − c,Sr_c)CoO₃ solid solutions: ab initio thermodynamic study