A Contribution to the Phase Diagram of the Quasibinary System Pb[S(1−x)Te
 x
 ]

Leute, Volkmar; Volkmer, Norbert

doi:10.1524/zpch.1985.144.144.145

Cited by 31 publications

(19 citation statements)

References 3 publications

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“…8(a) with the experimental miscibility gap, 17 we find that qualitatively the overall topology and asymmetry of the experimental phase diagram is captured by our model. However, quantitatively the maximum temperature of the calculated miscibility gap is a factor of 1.7 higher than that of the experimental gap.…”

Section: Comparison With Experiments For Pb(ste)supporting

confidence: 56%

“…There have been numerous experimental studies of the equilibrium phase stability of these systems. [15][16][17][18][70][71][72][73][74][75][76][77][78][79][80] The first three systems mix on the anion sublattice of rocksalt, and the last three mix on the rocksalt cation sublattice. The model of coherent phase stability used here consists of three parts.…”

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

confidence: 99%

“…The temperature -composition phase diagram of Pb(S,Te) contains a miscibility gap; [15][16][17][18] a region where PbS and PbTe are not soluble in one another, and a PbS-rich phase may precipitate out of a PbTe-rich supersaturated solid solution. Within a miscibility gap, the solid solution can either be unstable or metastable with respect to phase separation; the boundary between these two regions is called the spinodal line.…”

Section: Introductionmentioning

confidence: 99%

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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: Comparison With Experiments For Pb(ste)supporting

confidence: 56%

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

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Doak

Wolverton

2012

Phys. Rev. B

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“…In Table 2 are also listed the critical values for spinodal demixing, which were calculated from these interaction parameters using the formulas given in [17]. It is interesting that, in accordance with [IS], the calculations for the system ZnSerTe(, yield an azeotropic point.…”

Section: Calculation Of Phase Diagrams the Quasibinary Phase Diagramsmentioning

confidence: 72%

“…1 and 2 by a computer program, are shown in the Figs. 2a -d. The thermodynamic formalism used for these calculations corresponds to that given in [17], but neglects a possible temperature dependence of the interaction parameters.…”

Section: Calculation Of Phase Diagrams the Quasibinary Phase Diagramsmentioning

confidence: 99%

The Phasediagram of the Semiconductor Alloy Zn_kHg_(1‐k)Se_lTe_(1‐l)

Leute

Plate

1989

Ber Bunsenges Phys Chem

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757(x), enlargement of the wavefunction of aggregated localized states and corresponding enhancement of the polarizability or type of the electronic transition, first or second order, further more precise measurements of el (0, x) and E~( W , X ) are necessary. A precise control of the x-dependence by coulometric titration is possible and a continuous variation of the w-dependence down t o low energies seems feasible. These experiments are underway. That measurements under the necessary high temperature conditions can be successfully performed is demonstrated in this paper. Phase Diagrams J Semiconductors / Solid Solutions 1 ThermodynamicsThe phase diagram of the quasiternary system ZnkHal -k)SelTe(l -1) was investigated by X-ray diffraction and DTA measurements. The phase diagrams of the quasibinary subsystems were recalculated using the interaction parameters determined from the isothermal quasiternary sections. The subsolidus region of the quasiternary system shows an extended miscibility gap inspite of complete solid solutions on the quasibinary edges. The tie line field is fan shaped converging on the ZnSe comer of the phase square. The enthalpies of pair formation in the sublattices are calculated using the model of 4-particle-clusters. It is also shown, that the assumption of random distribution for the clusters is a rather good approximation for the calculation of the quasiternary phase diagram.

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Analysis of Phase Separation in High Performance PbTe–PbS Thermoelectric Materials

Girard

Schmidt‐Rohr

Chasapis

et al. 2012

Adv Funct Materials

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Phase immiscibility in PbTe–based thermoelectric materials is an effective means of top‐down synthesis of nanostructured composites exhibiting low lattice thermal conductivities. PbTe1‐x Sx thermoelectric materials can be synthesized as metastable solid solution alloys through rapid quenching. Subsequent post‐annealing induces phase separation at the nanometer scale, producing nanostructures that increase phonon scattering and reduce lattice thermal conductivity. However, there has yet to be any study investigating in detail the local chemical structure of both the solid solution and nanostructured variants of this material system. Herein, quenched and annealed (i.e., solid solution and phase‐separated) samples of PbTe–PbS are analyzed by in situ high‐resolution synchrotron powder X‐ray diffraction, solid‐state 125Te nuclear magnetic resonance (NMR), and infrared (IR) spectroscopy analysis. For high concentrations of PbS in PbTe, e.g., x >16%, NMR and IR analyses reveal that rapidly quenched samples exhibit incipient phase separation that is not detected by state‐of‐the‐art synchrotron X‐ray diffraction, providing an example of a PbTe thermoelectric “alloy” that is in fact phase inhomogeneous. Thermally‐induced PbS phase separation in PbTe–PbS occurs close to 200 °C for all compositions studied, and the solubility of the PbS phase in PbTe at elevated temperatures >500 °C is reported. The findings of this study suggest that there may be a large number of thermoelectric alloy systems that are phase inhomogeneous or nanostructured despite adherence to Vegard's Law of alloys, highlighting the importance of careful chemical characterization to differentiate between thermoelectric alloys and composites.

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A Contribution to the Phase Diagram of the Quasibinary System Pb[S_(1−x)Te_x]

Cited by 31 publications

References 3 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

The Phasediagram of the Semiconductor Alloy Zn_kHg_(1‐k)Se_lTe_(1‐l)

Analysis of Phase Separation in High Performance PbTe–PbS Thermoelectric Materials

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A Contribution to the Phase Diagram of the Quasibinary System Pb[S(1−x)Te x ]

Cited by 31 publications

References 3 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

The Phasediagram of the Semiconductor Alloy ZnkHg(1‐k)SelTe(1‐l)

Analysis of Phase Separation in High Performance PbTe–PbS Thermoelectric Materials

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Product

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A Contribution to the Phase Diagram of the Quasibinary System Pb[S_(1−x)Te_x]

The Phasediagram of the Semiconductor Alloy Zn_kHg_(1‐k)Se_lTe_(1‐l)