Predicting Dirac semimetals based on sodium ternary compounds

Peng, Bo; Yue, Changming; Zhang, Hao; Fang, Zhong; Weng, Hongming

doi:10.1038/s41524-018-0124-5

Cited by 19 publications

(7 citation statements)

References 45 publications

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“…8, there is no phonon mode with negative frequency in the phonon spectra of P 6 3 /mmc NaCaBi under pressures from 0 GPa to 10 GPa, which indicates that the metastable P 6 3 /mmc phase could be quenched to ambient pressure if they can be synthesized at higher pressure. These results are in accordance with the earlier work 37,38 . As shown in Fig.…”

Section: A the Crystal Structures Of Stoichiometric Nacabisupporting

confidence: 94%

Topological insulators in the NaCaBi family with large SOC gaps

Shao,

Guo,

et al. 2021

Preprint

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By means of first-principles calculations and crystal structure searching techniques, we predict that a new NaCaBi family crystallized into the ZrBeSi-type structure (i.e., P 63/mmc) are strong topological insulators (STIs). Taking P 63/mmc NaCaBi as an example, the calculated band structure indicates that there is a band inversion between two opposite-parity bands at the Γ point. In contrast to the well-known Bi2Se3 family, the band inversion in the NaCaBi family has already occured even without spin-orbit coupling (SOC), giving rise to a nodal ring surrounding Γ in the kz = 0 plane (protected by Mz symmetry). With time reversal symmetry (T ) and inversion symmetry (I), the spinless nodal-line metallic phase protected by [T I] 2 = 1 is the weak-SOC limit of the spinful topological insulating phase. Upon including SOC, the nodal ring is gapped, driving the system into a STI. Besides inversion symmetry, the nontrivial topology of NaCaBi can also be indicated by 6 symmetry. More surprisingly, the SOC-induced band gap in NaCaBi is about 0.34 eV, which is larger than the energy scale of room temperature. Four other compounds (KBaBi, KSrBi, RbBaBi and RbSrBi) in the family are stable at ambient pressure, both in thermodynamics and lattice dynamics, even though the gaps of them are smaller than that of NaCaBi. Thus, they provide good platforms to study topological states both in theory and experiments.

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Section: A the Crystal Structures Of Stoichiometric Nacabisupporting

confidence: 94%

Topological insulators in the NaCaBi family with large SOC gaps

Shao,

Guo,

et al. 2021

Preprint

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“…The paraelectric to ferroelectric phase transition temperature is lying slightly above room temperature, leading to a ferroelectric rhombohedral phase for x = 0.075 at ambient conditions, confirmed via X-ray diffraction and Raman spectroscopic studies. Thus the dielectric study suggests that the effect of Sn(x) doping on phase transition behaviour of BCZTSnx is similar to the one reported for Ba(Sn x Ti 1−x )O 3 and Ba(Zr x Ti 1−x )O 3 ceramics [10,23]. On further increasing Sn(x) content, both the real ( ) and imaginary ( ) parts of the dielectric permittivity show that the paraelectric (cubic) to ferroelectric (rhombohedral) phase transition shifts towards low temperatures, leading to the stabilization of a (cubic+rhombohedral) phase coexistence at room temperature for x = 0.10 in accordance with the X-ray diffraction and Raman spectroscopic analysis.…”

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confidence: 80%

Role of phonon mode in the enhancement of ferroelectric polarization in a perovskite-based eco-friendly functional material

Dubey¹,

Singh²,

Tripathi³

2022

EPL

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We report here the role of component freezing of three dimensional polar (Γ4-) phonon mode corresponding to the center of cubic Brillouin zone in tuning the structure-property correlations of a scientifically enriched and technologically important barium titanate based eco-friendly functional material (Ba0.92Ca0.08)(Zr0.05Ti0.95-xSnx)O3; BCZTSnx (0 ≤ x ≤ 0.10) synthesized via solid-state reaction method. The combined X-ray diffraction, Raman spectroscopic analysis, and temperature-dependent dielectric studies have revealed the presence of several crystallographic phase transitions with coexisting phases viz., P4mm→(P4mm + Amm2 + R3m)→(Amm2 + R3m)→R3m→(Pm3m+R3m), as a function of Sn(x) content. These crystallographic phases viz; P4mm, Amm2, and R3m results due to freezing of the component(s) of Γ4- phonon mode (belonging to Pm3m space group), with the respective order parameter directions (0,0,a), (a,a,0), and (a,a,a) leading to ferroelectric polarization along ⟨001⟩, ⟨110⟩ and ⟨111⟩ directions, respectively. The ceramic composition corresponding to x=0.025 exhibits a significant reduction in the coercive field (Ec) and an enhancement in ferroelectric polarization (Pr) in comparison to x=0, inferred from PE loop measurements. The enhancement in ferroelectric polarization at x=0.025 has been attributed to the inter-ferroelectric threephase (P4mm + Amm2 + R3m) coexistence around this composition, and significantly enhanced amplitudes of ferroelectric phonon modes corresponding to orthorhombic and rhombohedral phases, calculated using the symmetry mode analysis technique. The existence of a high ferroelectric polarization and low coercive field may lead to x=0.025 composition as an eco-friendly candidate for ferroelectric memory devices.

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“…[17] Given this importance of the SEI, understanding the electrode/electrolyte interface has presented itself as a crucial part of improving battery performance and has been the focus of numerous studies, utilizing experimental and theoretical approaches. [18][19][20][21][22][23] One established theoretical approach for investigating the SEI formation is ab initio molecular dynamic simulation (AIMD), [18,24] which enables atomistic insights into reactions/interactions between electrolyte components and the battery anode. DFT-based AIMD simulations are generally limited by their comparatively high calculational cost, leading to short simulation times.…”

Section: Introductionmentioning

confidence: 99%

Toward the Formation of the Solid Electrolyte Interphase on Alkaline Metal Anodes: Ab Initio Simulations**

Stottmeister¹,

Groß

2023

Batteries & Supercaps

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The transition from lithium‐based energy storage to post lithium systems plays a crucial part in achieving an environmentally sustainable energy infrastructure. Prime candidates for the replacement of lithium are sodium and potassium batteries. Despite being critical to battery performance, the solid electrolyte interphase (SEI) formation process for Na and K batteries remains insufficiently understood, especially compared to the well‐established lithium systems. Using ab initio molecular dynamics (AIMD) simulations based on density functional theory (DFT) calculations, we study the first steps of SEI formation upon the decomposition of typical solvent molecules on lithium, sodium and potassium metal anodes. We find that two dominant products form during the early SEI formation of cyclical carbonates on alkali metal anodes, carbon monoxide and alkali‐carbonate. The carbonate‐producing reaction is thermodynamically favorable for all tested metals, however, Na and K exhibit a much stronger selectivity than Li towards carbonate formation. Furthermore, we propose a previously unknown reaction mechanism for the CO polymerization on metallic lithium.

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Predicting Dirac semimetals based on sodium ternary compounds

Cited by 19 publications

References 45 publications

Topological insulators in the NaCaBi family with large SOC gaps

Topological insulators in the NaCaBi family with large SOC gaps

Role of phonon mode in the enhancement of ferroelectric polarization in a perovskite-based eco-friendly functional material

Toward the Formation of the Solid Electrolyte Interphase on Alkaline Metal Anodes: Ab Initio Simulations**

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