Elementary energy bands in isovalent IV–VI orthorhombic and cubic crystals and their solid solutions

Slipukhina, Ivetta; Bercha, D. M.

doi:10.1002/pssb.200642263

Cited by 17 publications

(14 citation statements)

References 47 publications

(65 reference statements)

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“…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] of these materials. In addition, several studies have looked at the phase stability of these systems, calculating ...…”

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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“…It should be pointed out that M-M bonding is possible for some p-block elements, but it won't change the electronic configuration and coordination geometry. The situation becomes more complex for Ge and Sn, as they can be stabilized in both a +2 oxidation state with an electron lone pair and a +4 oxidation state typically in a tetrahedral environment, as shown by a number of compounds ranging from binary to quaternary ones such as MQ (M = Ge, Sn; Q = S, Se), [28][29][30][31] MQ 2 (M = Ge, Sn; Q = S, Se), [32][33][34][35] and A 2 Hg 3 M 2 S 8 (A = K, Rb; M = Ge, Sn). 13 The mixed valence property of Ge and Sn will increase diversity in their stoichiometry and structure.…”

Section: Introductionmentioning

confidence: 99%

Ba6Sn6Se13: a new mixed valence selenostannate with NLO property

et al. 2013

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A new ternary selenostannate Ba6Sn6Se13 has been synthesized by a high temperature solid-state method. The compound crystallizes in the non-centrosymmetric orthorhombic space group P2(1)2(1)2(1) and may be represented as Ba6Sn5(2+)Sn(4+)Se13 with mixed valence Sn atoms. Sn(4+) cations lie in a tetrahedral environment, while Sn(2+) cations are found in two kinds of coordination environments: the trigonal pyramid and quadrangular pyramid. SnSe(n) (n = 3, 4, 5) polyhedra are further connected to generate a three-dimensional framework with Ba(2+) residing in cavities. Ba6Sn6Se13 shows moderate nonlinear optical response and is the first reported NLO compound in the Ba-Sn-Se system. In addition, diffuse reflectance spectroscopy measurement indicates that the band gap of Ba6Sn6Se13 is 1.52(2) eV and thermal analysis suggests that the compound melts incongruently. The theoretically calculated SHG response and band gap are in good agreement with experimental results.

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“…Although SnS is well-studied, Pb 0.5 Sn 0.5 S and Pb x Sn (1 − x) S series are not investigated in detail. The theoretically calculated energy band gap values for Pb 0.5 Sn 0.5 S are 0.64 eV [33] and 1.1 eV [34]. Experimental measurements of Pb 0.5 Sn 0.5 S optical energy band gap reveal E g(d) = 1.65 eV for direct transitions and E g(i) = 0.96 eV for indirect transitions [37].…”

Section: Introductionmentioning

confidence: 81%

Influence of annealing on microstructure and optical properties of hot wall deposited PbxSn(1−x)S thin films

et al. 2016

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Pb x Sn (1 − x) S (0.05 b x b 0.20) thin films with the thickness of 2 μm were deposited on glass substrates using hot wall vacuum deposition method at the vacuum pressure of 5 × 10 −4 Pa, wall temperature of 600°С, substrate temperature of 300°С and subsequently annealed at 450°C in vacuum at 5 × 10 −4 Pa. The microstructure and optical properties of the as-deposited and annealed films were examined in relation to the film composition. The explanations of lattice parameter deviations from the bulk crystals for both as-deposited and annealed Pb x Sn (1 − x) S thin films are discussed. The Pb x Sn (1 − x) S thin films exhibit a preferred orientation around the [111] direction. The annealing decreases the film microstrain values and increases the grain size and the degree of preferred orientation. Thermal probe measurements showed the sulfur-deficient films to be p-type and the sulfur-rich films to be n-type. The Pb x Sn (1 − x) S films exhibit direct allowed transitions with energy band gap E g(d) increasing with the increase of Pb mole fraction. The E g(d) values for as-deposited films range from 0.95 to 0.98 eV and for annealed films they variy from 0.90 to 0.94 eV.

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Elementary energy bands in isovalent IV–VI orthorhombic and cubic crystals and their solid solutions

Cited by 17 publications

References 47 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

Ba6Sn6Se13: a new mixed valence selenostannate with NLO property

Influence of annealing on microstructure and optical properties of hot wall deposited PbxSn(1−x)S thin films

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