LO-mode phonon of KCl and NaCl at 300 K by inelastic x-ray scattering measurements and first principles calculations

Togo, Atsushi; Hayashi, Hiroyuki; Tadano, Terumasa; Tsutsui, Satoshi; Tanaka, Isao

doi:10.1088/1361-648x/ac7b01

Cited by 23 publications

(32 citation statements)

References 56 publications

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“…43 We have investigated the dynamic stability of the hexagonal MAX phases by phonon spectra at finite temperatures (0, 4, 77, and 293 K) using the stochastic self-consistent harmonic approximation. 39,40 The results are included in the Supporting information file. Interestingly, in some MAX phases, the instability already vanishes at helium temperature and in some systems at liquid nitrogen temperature, whereas in some systems, the phonon instability persists at room temperature.…”

Section: Resultsmentioning

confidence: 99%

“…The forces of the supercells with the generated displacements were calculated using the VASP code 23−27 and were used for the fitting of force constants. 39,40 ■…”

Section: ■ Methods Of Calculationsmentioning

confidence: 99%

“…The dynamic stabilities of the MAX phases at finite temperatures (0, 4, 77, and 293 K) were studied using anharmonic phonon calculations by applying the stochastic self-consistent harmonic approximation. , For the calculation of the force constants, we carried out a series of 3 × 3 × 1 supercell calculations (50) in which the atoms were randomly displaced from their equilibrium positions based on the chosen temperature. The forces of the supercells with the generated displacements were calculated using the VASP code − and were used for the fitting of force constants. , …”

Section: Methods Of Calculationsmentioning

confidence: 99%

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Superlattice MAX Phases with A-Layers Reconstructed into 0D-Clusters, 1D-Chains, and 2D-Lattices

et al. 2023

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MAX phases are layered non-van der Waals materials made by stacking hexagonal layers of transition metal (M), a group III–VI element (A), and carbon or nitrogen (X) with the conventional chemical formula M n+1 AX n (n = 1–3). According to our recent high-throughput calculations, 761 dynamically stable MAX phases have been found, among which 466 structures are likely to be synthesized. To find completely new structural phases, we focus on the 361 MAX systems with dynamical instabilities. A series of novel superlattices are discovered for MAX phases by reconstructing the triangular lattice of A-atoms into 0D-clusters, quasi-1D-chain, or the creation of 2D Haeckelite or Kagome-like lattices. This work opens a new avenue for discovering novel MAX phases from conventional structures without any element alloying.

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Section: Resultsmentioning

confidence: 99%

“…The forces of the supercells with the generated displacements were calculated using the VASP code 23−27 and were used for the fitting of force constants. 39,40 ■…”

Section: ■ Methods Of Calculationsmentioning

confidence: 99%

Section: Methods Of Calculationsmentioning

confidence: 99%

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Superlattice MAX Phases with A-Layers Reconstructed into 0D-Clusters, 1D-Chains, and 2D-Lattices

et al. 2023

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“…A possible application is to embed anharmonic contribution obtained through self-consistent harmonic approximation using a smaller supercell into the harmonic force constants of a larger supercell. 20…”

Section: Transformation Between Force Constants and Dynamical Matricesmentioning

confidence: 99%

“…41,42 An application of SSCHA performed with random displacements generated by the phonopy code coupled with the ALM force constants calculation code 43 is found in Ref. 20.…”

Section: Random Displacement Generationmentioning

confidence: 99%

Implementation strategies in phonopy and phono3py

Togo¹,

Chaput²,

Tadano³

et al. 2023

Preprint

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Scientific simulation codes are public property sustained by the community. Modern technology allows anyone to join scientific software projects, from anywhere, remotely via the internet.The phonopy and phono3py codes are widely used open source phonon calculation codes. This review describes a collection of computational methods and techniques as implemented in these codes and shows their implementation strategies as a whole, aiming to be useful for the community. Some of the techniques presented here are not limited to phonon calculations and may therefore be useful in other area of condensed matter physics.

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Chalcogenide Perovskite Thin Films with Controlled Phases for Optoelectronics

Yu,

Hui,

West

et al. 2023

Adv Funct Materials

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Chalcogenide perovskites have emerged as promising semiconductor materials due to their appealing properties, including tunable bandgaps, high absorption coefficients, reasonable carrier lifetimes and mobilities, excellent chemical stability, and environmentally benign nature. However, beyond the well‐studied BaZrS3, reports on chalcogenide perovskite thin films with diverse compositions are scarce. In this study, the realization of four different types of chalcogenide perovskite thin films with controlled phases, through CS2 annealing of amorphous chalcogenide precursor films deposited by pulsed laser deposition (PLD), is reported. This achievement is guided by a thorough theoretical investigation of the phase stability of chalcogenide perovskites. Upon crystallization in the distorted perovskite phase, all materials exhibit photoluminescence (PL) with peak positions in the visible range, consistent with their expected bandgap values. However, the full‐width‐at‐half‐maximum (FWHM) of the PL spectra varies significantly across these materials, ranging from 99 meV for SrHfS3 to 231 meV for BaHfS3. The difference is attributed to the difference in kinetic barriers between local structural motifs for the Sr and Ba compounds. The findings underscore the promise of chalcogenide perovskite thin films as an alternative to traditional halide perovskites for optoelectronic applications, while highlighting the challenges in optimizing their synthesis and performance.

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LO-mode phonon of KCl and NaCl at 300 K by inelastic x-ray scattering measurements and first principles calculations

Cited by 23 publications

References 56 publications

Superlattice MAX Phases with A-Layers Reconstructed into 0D-Clusters, 1D-Chains, and 2D-Lattices

Superlattice MAX Phases with A-Layers Reconstructed into 0D-Clusters, 1D-Chains, and 2D-Lattices

Implementation strategies in phonopy and phono3py

Chalcogenide Perovskite Thin Films with Controlled Phases for Optoelectronics

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