Structural stability, dynamical stability, thermoelectric properties, and elastic properties of GeTe at high pressure

Kagdada, Hardik L.; Jha, Prafulla K.; Śpiewak, Piotr; Kurzydłowski, Krzysztof J.

doi:10.1103/physrevb.97.134105

Cited by 45 publications

(20 citation statements)

References 62 publications

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“…The dynamical and mechanical stabilities of A 2 AgRhCl 6 were examined using computed phonon band structures and elastic properties, respectively (Mouhat and Coudert, 2014;Togo and Tanaka, 2015;Kagdada et al, 2018). The former calculations were carried out using Phonopy (Togo and Tanaka, 2015).…”

Section: Computational Detailsmentioning

confidence: 99%

The Cs2AgRhCl6 Halide Double Perovskite: A Dynamically Stable Lead-Free Transition-Metal Driven Semiconducting Material for Optoelectronics

Varadwaj

Marques

2020

Front. Chem.

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A-Site doping with alkali ions, and/or metal substitution at the B and B ′-sites, are among the key strategies in the innovative development of A 2 BB ′ X 6 halide double perovskite semiconducting materials for application in energy and device technologies. To this end, we have investigated an intriguing series of five halide-based non-toxic systems, A 2 AgRhCl 6 (A = Li, Na, K, Rb, and Cs), using density functional theory at the SCAN-rVV10 level. The lattice stability and bonding properties emanating from this study of A 2 AgRhCl 6 matched well with those that have already been synthesized, characterized and discussed [viz. Cs 2 AgBiX 6 (X = Cl, Br)]. Exploration of traditional and recently proposed tolerance factors has enabled us to identify A 2 AgRhCl 6 (A = K, Rb and Cs) as stable double perovskites. The band structure and density of states calculations suggested that the electronic transition from the top of the valence band [Cl(3p)+Rh(4d)] to the bottom of the conduction band [(Cl(3p)+Rh(4d)] is inherently direct at the X-point of the first Brillouin zone. The (non-spin polarized) bandgap of these materials was found in the range 0.57-0.65 eV with SCAN-rVV10, which were substantially smaller than those computed with hybrid HSE06 and PBE0, and quasi-particle GW methods. This, together with the appreciable refractive index and high absorption coefficient in the region covering the range 1.0-4.5 eV, enabled us to demonstrate that A 2 AgRhCl 6 (A = K, Rb, and Cs) are likely candidate materials for photoelectric applications. The results of our phonon calculations at the harmonic level suggested that the Cs 2 AgRhCl 6 is the only system that is dynamically stable (no imaginary frequencies found around the high symmetry lines of the reciprocal lattice), although the elastic moduli properties suggested all five systems examined are mechanically stable. Keywords: A 2 AgRhCl 6 halide double perovskites, first-principles studies, optoelectronic properties, geometrical, dynamical and mechanical stabilities, DOS and band structures Varadwaj and Marques Stable Halide Double Perovskites

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Section: Computational Detailsmentioning

confidence: 99%

The Cs2AgRhCl6 Halide Double Perovskite: A Dynamically Stable Lead-Free Transition-Metal Driven Semiconducting Material for Optoelectronics

Varadwaj

Marques

2020

Front. Chem.

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“…In this respect, the addition of Se into GeTe has been considered recently 14 and results on thin films indicate that with Se addition the contrast in electrical resistivity could be increased up to a factor of 100 between the amorphous and crystalline material states 15 , other properties being continuously controlled by Se content such as resistance, bandgap, transition temperature and threshold voltage. Here, we remind that the c-GeTe occurs in two forms: a trigonal R 3m symmetry that is stable at ambient conditions 16 up to 50-50.5 at.% Te and a cubic rocksalt structure stable at high temperatures. The nature of these phases as well as their stability has been examined in Ref.…”

Section: Introductionmentioning

confidence: 99%

Alteration of structural, electronic, and vibrational properties of amorphous GeTe by selenium substitution: An experimentally constrained density functional study

et al. 2021

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The structural, vibrational and electronic properties of several compositions of amorphous Ge-Se-Te are studied from a combination of X-ray diffraction and density functional-based molecular dynamics. Different structural properties are considered such as structure factors, pair distribution functions, angular distributions, coordination numbers and neighbor distributions. We compare results with experimental findings and a satisfying agreement is found for the structure functions in real and reciprocal spaces. The short range order is found to be more complex than in related binaries that result in mixed geometries ( 65-75 % tetrahedral, and remaining defect octahedral) for a dominant four-fold Ge (80 %). The chalcogen atoms are dominantly 2-fold, the former having furthermore an important fraction of 3-fold coordinated atoms (30-40 %). The obtained model structures indicate that Ge-Ge, Ge-Se, and Ge-Te bonds dominate with small fractions of Te-Te bonds remaining from the base system GeTe. The investigation of electronic properties indicates that the addition of Se atoms will lead to Te-related bands that are much more localized so that Ge-Te-Se can be regarded as having an increased covalent character with respect to GeTe.

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“…4 (a)). The ferroelectric distortion of GeTe corresponds to A 1 and E IRs of its C 3v point group symmetry [40,41]. These allow the t I], and the corresponding MCP has more components than in the case of PTO.…”

Section: Ir Multipole Real Spacementioning

confidence: 99%

Magnetic Compton profile in non-magnetic ferroelectrics

Bhowal,

Collins,

Spaldin

2021

Preprint

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Magnetic Compton scattering is an established tool for probing magnetism in ferromagnetic or ferrimagnetic materials with a net spin polarization. Here we show that, counterintuitively, nonmagnetic systems can also have a non-zero magnetic Compton profile, provided that space-inversion symmetry is broken. The magnetic Compton profile is antisymmetric in momentum and, if the inversion symmetry is broken by an electric-field switchable ferroelectric distortion, can be reversed using an electric field. We show that the underlying physics of the magnetic Compton profile and its electrical control are conveniently described in terms of k-space magnetoelectric multipoles, which are reciprocal to the real-space charge dipoles associated with the broken inversion symmetry. Using the prototypical ferroelectric lead titanate, PbTiO3, as an example, we show that the ferroelectric polarization introduces a spin asymmetry in momentum space that corresponds to a pure k-space magnetoelectric toroidal moment. This in turn manifests in an antisymmetric magnetic Compton profile which can be reversed using an electric field. Our work suggests an experimental route to directly measuring and tuning hidden k-space magnetoelectric multipoles via their magnetic Compton profile.

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Structural stability, dynamical stability, thermoelectric properties, and elastic properties of GeTe at high pressure

Cited by 45 publications

References 62 publications

The Cs2AgRhCl6 Halide Double Perovskite: A Dynamically Stable Lead-Free Transition-Metal Driven Semiconducting Material for Optoelectronics

The Cs2AgRhCl6 Halide Double Perovskite: A Dynamically Stable Lead-Free Transition-Metal Driven Semiconducting Material for Optoelectronics

Alteration of structural, electronic, and vibrational properties of amorphous GeTe by selenium substitution: An experimentally constrained density functional study

Magnetic Compton profile in non-magnetic ferroelectrics

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