Electron-poor antimonides: complex framework structures with narrow band gaps and low thermal conductivity

Häußermann, Ulrich; Mikhaylushkin, A. S.

doi:10.1039/b915724g

Cited by 29 publications

(47 citation statements)

References 46 publications

(39 reference statements)

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“…In terms of their bonding and structural features we may interpret the weakly ionic II-V semiconductors as a bridge between boron (with an electron count of 3 e/atom) and the tetrahedrally bonded semiconductors (with an electron count of 4 e/per atom). 55 This is also reflected in the coordination number of atoms which is 5 in II-V semiconductors and, thus, intermediate between those of elemental boron structures (6 or 7) and the tetrahedrally bonded II-VI and III-V systems (4), where atoms are exclusively connected by 2c2e bonds. .…”

Section: Discussionmentioning

confidence: 99%

Electronic structure and chemical bonding of the electron-poor II-V semiconductors ZnSb and ZnAs

2011

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The binary compounds ZnSb and ZnAs with the CdSb structure are semiconductors (II-V), although the average electron concentration (3.5 per atom) is lower than that of the tetrahedrally bonded III-V and II-VI archetype systems (4 per atom). We report a detailed electronic structure and chemical bonding analysis for ZnSb and ZnAs based on first principles calculations. ZnSb and ZnAs are compared to the zinc blende type semiconductors GaSb, ZnTe, GaAs, and ZnSe, as well as the more ionic, hypothetical, II-V systems MgSb and MgAs. We establish a clearly covalent bonding scenario for ZnSb and ZnAs where multicenter bonded structural entities (rhomboid rings Zn 2 Sb 2 and Zn 2 As 2 ) are connected to each other by classical two-center, twoelectron bonds. This bonding scenario is only compatible with a weak ionicity in II-V semiconductor systems and appears to be strongly coupled to the stability of the CdSb structure type. It is argued that a chemical bonding scenario with mixed multicenter and two-center bonding resembles that of boron and boron rich compounds, and is typical of electron poor spbonded semiconductors with average valence electron concentrations below 4 per atom.2

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Section: Discussionmentioning

confidence: 99%

Electronic structure and chemical bonding of the electron-poor II-V semiconductors ZnSb and ZnAs

2011

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“…Therefore, all the atoms in the crystal structure are bonded together in a network. ZnSb, thereby, has been classified as an electron-poor framework semiconductor (EPFS) [26,31]. A quite similar interpretation for the structure has been applied to the related compounds CdSb [30,[32][33][34] and ZnAs [35].…”

Section: Crystallographic Structure and Covalent Bondsmentioning

confidence: 99%

“…The band structure of ZnSb has been calculated by ab-initio methods by many groups in recent years [2,26,31,[36][37][38][39][40][41][42]. The calculations are based upon density functional theory (DFT), but with varying detailed approximations and trade-offs between computational cost and accuracy.…”

Section: Band Calculationsmentioning

confidence: 99%

Review of Research on the Thermoelectric Material ZnSb

Song¹,

Finstad²

2016

Thermoelectrics for Power Generation - A Look at Trends in the Technology

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The thermoelectric material ZnSb has been studied intensively in recent years and has shown promising features. The other zinc-antimonide compound, Zn 4 Sb 3 has remarkable low thermal conductivity, but it is accompanied with phase transitions at moderate temperature and has inherent stability problems. Compared to that, ZnSb is relatively phase stable and has a relative high charge carrier mobility and Seebeck coefficient, thus yielding a decent power factor. Meanwhile, its thermal conductivity can be reduced by means of nanostructuring, thus giving a good figure of merit at moderate temperatures, 400-600K. Many researchers have dedicated their efforts to study and improve ZnSb properties, and the figure of merit has been reported to be above one. Still, ZnSb as a thermoelectric material has features and behaviours that are not well-understood. The behaviour and properties of its intrinsic defects are not understood, but have interested researchers in recent years. This chapter intends to offer a comprehensive review on ZnSb to the readers. By combining own experiences from research on thermoelectric materials, the authors address the prospect for improving the thermoelectric properties of ZnSb and the concerns of transferring lab results to manufacturing.

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“…There are three additional interstitial sites for Zn atoms (Zn2, Zn3, and Zn4) with partial occupancy of about 5% (36 available positions for each site). These interstitial Zn atoms make up for the electron-poor nature of main structure so that the charge balance is achieved 91 . Therefore, the partially occupied interstitial sites lead to significant point-defect scatterings 96 .…”

Section: Effect Of Ag Addition On Cdsbmentioning

confidence: 99%

Thermal conductivity switch: Optimal semiconductor/metal melting transition

Kim

Kaviany

2016

Phys. Rev. B

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Scrutinizing distinct solid/liquid (s/l) and solid/solid (s/s) phase transitions (passive transitions) for large change in bulk (and homogenous) thermal conductivity, we find the s/l semiconductor/metal (S/M) transition produces largest dimensionless thermal conductivity switch (TCS) figure of merit Z TCS (change in thermal conductivity divided by smaller conductivity). At melting temperature, the solid phonon and liquid molecular thermal conductivities are comparable and generally small, so the TCS requires localized electron solid and delocalized electron liquid states.For cyclic phase reversibility, the congruent phase transition (no change in composition) is as important as the thermal transport. We identify XSb and XAs (X = Al, Cd, Ga, In, Zn) and describe atomic-structural metrics for large Z TCS , then show the superiority of S/M phonon-to electrondominated transport melting transition. We use existing experimental results and theoretical and ab initio calculations of the related properties for both phases (including the Kubo-Greenwood and Bridgman formulations of liquid conductivities). The 5p orbital of Sb contributes to the semiconductor behavior in the solid-phase bandgap and upon disorder and bond-length changes in the liquid phase this changes to metallic, creating the large contrast in thermal conductivity.The charge density distribution, electronic localization function, and electron density of states are used to mark this S/M transition. For optimal TCS, we examine the elemental selection from the transition-, basic-and semimetals and semiconductor groups. For CdSb, addition of residual Ag suppresses the bipolar conductivity and its Z TCS is over 7, and for Zn 3 Sb 2 it is expected to be over 14, based on the structure and transport properties of the better known β-Zn 4 Sb 3 . This is the highest Z TCS identified. In addition to the metallic melting, the high Z TCS is due to the electron-poor nature of II-V semiconductors leading to the significantly low phonon conductivity.

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Electron-poor antimonides: complex framework structures with narrow band gaps and low thermal conductivity

Cited by 29 publications

References 46 publications

Electronic structure and chemical bonding of the electron-poor II-V semiconductors ZnSb and ZnAs

Electronic structure and chemical bonding of the electron-poor II-V semiconductors ZnSb and ZnAs

Review of Research on the Thermoelectric Material ZnSb

Thermal conductivity switch: Optimal semiconductor/metal melting transition

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