Polymorphism of As2Te3: structural studies and thermal behaviour of rhombohedral β-As2Te3

Toscani, Siro; Dugué, Jérôme; Ollitrault, Rolande; Céolin, R.

doi:10.1016/0040-6031(91)87040-4

Cited by 21 publications

(17 citation statements)

References 6 publications

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“…It's well known that the b variety is denser than the stable a form. 23 This conclusion seems to be further corroborated by neutron thermodiffraction experiments carried out to determine not only the nature of the phase crystallizing in the glassy matrix but also their evolution upon heating. Fig.…”

Section: Glass-ceramics Formation and Microstructurementioning

confidence: 72%

“…The applied pressure during the SPS process together with internal stresses thus likely plays an important role in the stabilization of the b phase. 23 Upon closer inspection of Fig. 3 (patterns h and g), it can be noticed that, even in the most crystallized sample, the reections corresponding to b-As 2 Te 3 in the PXRD pattern are broad likely due to the size of the precipitates and/or microstrains.…”

Section: Glass-ceramics Formation and Microstructurementioning

confidence: 95%

“…While a-As 2 Te 3 (monoclinic structure, space group C2/m) 20 is stable under ambient conditions and can be easily synthesized by conventional solid-state synthesis routes, the b-As 2 Te 3 allotropic structure (rhombohedral structure of Bi 2 Te 3 structure type, space group R 3m) [20][21][22] is metastable and so far could only be synthesized under highpressure or by rapid quenching. [20][21][22][23] The fact that the metastable high-pressure b-As 2 Te 3 phase is favored in the glass may be due to the constraint of the material through an applied pressure during the SPS process. It's well known that the b variety is denser than the stable a form.…”

Section: Glass-ceramics Formation and Microstructurementioning

confidence: 99%

See 2 more Smart Citations

A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

et al. 2013

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Section: Glass-ceramics Formation and Microstructurementioning

confidence: 72%

Section: Glass-ceramics Formation and Microstructurementioning

confidence: 95%

Section: Glass-ceramics Formation and Microstructurementioning

confidence: 99%

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A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

et al. 2013

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“…As 2 Te 3 is also very interesting since it has the ability to display rich polymorphism for different experimental conditions (temperature and/or pressure) such as the metastable tetradymite structure (β-As 2 Te 3 ) [5,[10][11][12] and the lowtemperature phase with P2 1 /m symmetry (β -As 2 Te 3 ) [13]. In particular, several theoretical studies have addressed the structural, mechanical, and electronic properties of β-As 2 Te 3 at room conditions [14][15][16][17][18] and it has been experimentally demonstrated that this phase also displays good thermoelectric properties [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

β−As2Te3 : Pressure-induced three-dimensional Dirac semimetal with ultralow room-pressure lattice thermal conductivity

et al. 2021

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An ab initio study of β-As 2 Te 3 (R 3m symmetry) at hydrostatic pressures shows that this compound is a trivial small band-gap semiconductor at room pressure that undergoes a quantum topological phase transition to a 3D topological Dirac semimetal around 2 GPa. At higher pressures, the band gap reopens and again decreases above 4 GPa. Our calculations predict an insulator-metal transition above 6 GPa due to the closing of the band gap, with strong topological features persisting between 2 and 10 GPa with Z 4 = 3 topological index. By investigating the lattice thermal conductivity (κ L ), we observe that close to room conditions κ L is very low, either for the in-plane and the out-of-plane axis, with 0.098 and 0.023 Wm −1 K −1 , respectively. This effect occurs due to the presence of two low-frequency optical modes, namely E u and E g , which increase the phonon-phonon scattering rate. Therefore, our results suggest that ultralow lattice thermal conductivities, which enable highly efficient thermoelectric materials, can be engineered in systems that are close to a structural instability derived from phonon Kohn anomalies. At higher pressures, the values of the in-and out-of-plane thermal conductivities not only increase in magnitude, but also approximate in value as the layered character of the compound decreases.

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“…The high pressure study of α-As 2 Te 3 by Scheidemantel et el 10 revealed a pressure induced structural phase transition from monoclinic (α-As 2 Te 3 ) to rhombohedral structure (β-As 2 Te 3 ) near 7 GPa, leading to dramatic enhancement in its thermoelectric power. The β-As 2 Te 3 phase can also be synthesized by rapid quenching from high temperature or by compressing monoclinic α-As 2 Te 3 crystals [11][12][13] .…”

mentioning

confidence: 99%

Strain induced Z2 topological insulating state of β-As2Te3

Pal

Waghmare

2014

Applied Physics Letters

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Topological insulators are non-trivial quantum states of matter which exhibit a gap in the electronic structure of their bulk form, but a gapless metallic electronic spectrum at the surface. Here, we predict a uniaxial strain induced electronic topological transition (ETT) from a band to topological insulating state in the rhombohedral phase (space group: R3m) of As 2 Te 3 (β-As 2 Te 3 ) through first-principles calculations including spin-orbit coupling within density functional theory. The ETT in β-As 2 Te 3 is shown to occur at the uniaxial strain ǫ zz = -0.05 (σ zz =1.77 GPa), passing through a Weyl metallic state with a single Dirac cone in its electronic structure at the Γ point. We demonstrate the ETT through band inversion and reversal of parity of the top of the valence and bottom of the conduction bands leading to change in the Z 2 topological invariant ν 0 from 0 to 1 across the transition. Based on its electronic structure and phonon dispersion, we propose ultra-thin films of As 2 Te 3 to be promising for use in ultra-thin stress sensors, charge pumps and thermoelectrics. a) Electronic mail:waghmare@jncasr.ac.in 1

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Polymorphism of As2Te3: structural studies and thermal behaviour of rhombohedral β-As2Te3

Cited by 21 publications

References 6 publications

A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

β−As2Te3 : Pressure-induced three-dimensional Dirac semimetal with ultralow room-pressure lattice thermal conductivity

Strain induced Z2 topological insulating state of β-As2Te3

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