Theoretical study of phonon dispersion, elastic, mechanical and thermodynamic properties of barium chalcogenides

Musari, A. A.; Orukombo, S. A.

doi:10.1142/s0217979218500923

Cited by 8 publications

(3 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We first established a control calculation using the better-known electronic properties of rock salt BaSe. Both the band structure and DOS reveal an indirect band gap of 2.20 eV at the Γ and X high-symmetry points (see the Supporting Information), in close agreement with other computational studies. − This method underestimates the experimental band gap by 35%, which is consistent with the amount of variance typically observed using LMTO-ASA. , …”

Section: Resultssupporting

confidence: 87%

Alkaline-Earth Chalcogenide Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability

et al. 2022

View full text Add to dashboard Cite

Increasing demand for effective energy conversion materials and devices has renewed interest in semiconductors comprised of earth-abundant and biocompatible elements. Alkaline-earth sulfides doped with rare earth ions are versatile optical materials. However, relatively little is known about controlling the dimensionality, surface chemistry, and inherent optical properties of the undoped versions of alkaline-earth mono- and polychalcogenides. We describe the colloidal synthesis of alkaline-earth chalcogenide nanocrystals through the reaction of metal carboxylates with carbon disulfide or selenourea. Systematic exploration of the synthetic phase space allows us to tune particle sizes over a wide range using a mixture of commercially available carboxylate precursors. Solid-state NMR spectroscopy confirms the phase purity of the selenide compositions. Surface characterization reveals that bridging carboxylates and amines preferentially terminate the surface of the nanocrystals. While these materials are colloidally stable in the mother solution, the selenides are susceptible to oxidation over time, eventually degrading to selenium metal through polyselenide intermediates. As part of these investigations, we have developed the colloidal syntheses of barium di- and triselenides, two among few reported nanocrystalline alkaline-earth polychalcogenides. Electronic structure calculations reveal that both materials are indirect band gap semiconductors. The colloidal chemistry presented here may enable the synthesis of more complex, multinary chalcogenide materials containing alkaline-earth elements.

show abstract

Section: Resultssupporting

confidence: 87%

Alkaline-Earth Chalcogenide Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability

et al. 2022

View full text Add to dashboard Cite

show abstract

“…On the other hand, lattice dynamics of B1 phase is well studied at ambient as well as at high pressure using first principles calculations 16,51,56,57 and inelastic neutron scattering technique. 58 However, very limited studies 52 are available exploring lattice dynamics of high pressure phases, underlying mechanisms behind the observed structural phase transitions and spectroscopic properties under high pressure in BaO.…”

Section: Introductionmentioning

confidence: 99%

Lattice instability and Raman spectra of BaO under high pressure: A first principles study

Lavanya,

Yedukondalu,

Roshan

et al. 2022

Preprint

View full text Add to dashboard Cite

Alkaline-earth metal oxides, in particular MgO and CaO dominate Earth's lower mantle, therefore, exploring high pressure behavior of this class of compounds is of significant geophysical research interest. Among all these compounds, BaO exhibits rich polymorphism in the pressure range of 0-1.5 Mbar. Static enthalpy calculations revealed that BaO undergoes a pressure induced structural phase transition from NaCltype (B1) → NiAs-type (B8) → distorted CsCl-type (d-B2) → CsCl-type (B2) at 5.1, 19.5, 120 GPa respectively. B1 → B8 & B8 → d-B2 transitions are found to be first order in nature whereas d-B2→ B2 is a second order or weak first order phase transition. Interestingly, d-B2 phase shows stability over a wide pressure range, ∼19.5-113 GPa. Mechanical and dynamical stabilities of ambient and high pressure phases are demonstrated through computed elastic constants and phonon dispersion curves, respectively. Under high pressure, significant phonon softening and soft phonon mode along M-direction are observed for B8, d-B2 and B2 phases, respectively. Pressure dependent Raman spectra suggest a phase transition from d-B2 to Raman inactive phase under pressure. Overall, the present study provides a comprehensive understanding of underlying mechanisms behind pressure-induced structural phase transitions in BaO.

show abstract

“…The MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds are extensively studied from the theoretical perspective, which mainly focused on exploring the elastic, , lattice dynamics, − thermodynamic, , and thermoelectric properties − at ambient and/or high-pressure conditions. However, very limited studies have been dedicated toward understanding the phonon transport in MgSe, MgTe, CaX (X = O, S, Se, and Te) and MTe (M = Mg, Ca, Sr, Ba, and Pb) compounds.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

Roshan

Yedukondalu

Muthaiah

et al. 2021

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

Materials with an intrinsic (ultra)low lattice thermal conductivity (k L ) are critically important for the development of efficient energy conversion devices. In the present work, we have investigated microscopic origins of low k L behavior in BaO, BaS, and MgTe by exploring lattice dynamics and phonon transport of 16 isostructural MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds in the rocksalt (NaCl)-type structure. Anomalous trends are observed for k L in MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds except for the MgX (X = O, S, Se, and Te) series in contrast to the expected trend from their atomic mass. The underlying mechanisms for such low k L behavior in large mismatch atomic mass systems, namely, BaO, BaS, and MgTe, are thoroughly analyzed. We propose the following factors that might be responsible for low k L behavior in these materials: (1) high mass contrast provides a phonon gap between the acoustic and optic branches; (2) softening of transverse acoustic (TA) phonon modes due to the presence of heavy element; (3) low-lying optic (LLO) phonon modes fall into the acoustic mode region and are responsible for softening of the acoustic phonon modes or enhancing the overlap between LLO (TO) and longitudinal acoustic (LA) phonon modes, thereby increasing scattering rates; (4) shorter phonon lifetimes; and (5) a relatively high density (ρ) and a large Gruneisen parameter (γ) leads to strong anharmonicity. Moreover, tensile strain causes a further reduction in k L for BaO, BaS, and MgTe through phonon softening and near ferroelectric instability. Our comprehensive study on 16 binary MX (M = Mg, Ca, Sr, and Ba and X = O, S, Se, and Te) compounds provides a pathway for designing (ultra)low k L materials through phonon engineering even with simple crystal systems.

show abstract

Theoretical study of phonon dispersion, elastic, mechanical and thermodynamic properties of barium chalcogenides

Cited by 8 publications

References 36 publications

Alkaline-Earth Chalcogenide Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability

Alkaline-Earth Chalcogenide Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability

Lattice instability and Raman spectra of BaO under high pressure: A first principles study

Anomalous Lattice Thermal Conductivity in Rocksalt IIA–VIA Compounds

Contact Info

Product

Resources

About