A study of two-dimensional PbFCl and BaFCl

Manjunath, K.; Soni, Amit; Rao, C. N. R.

doi:10.1007/s12034-020-02117-3

Cited by 6 publications

(3 citation statements)

References 26 publications

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“…Recently, wide-band-gap layered semiconductors receive great attention due to potential applications in electronics and optoelectronics in the green and blue wavelength regions . In particular, PbClF-type (matlockite) materials attract interest because of their applications in photodetectors and optoelectronic devices. − Barhoumi et al have investigated the electronic and vibrational properties of several PbClF-type two-dimensional (2D) materials for possible utilization in optoelectronic devices. Tan et al have synthesized 2D lead halides and mixed halofluorides to develop low-cost, high-sensitivity, low-noise, and flexible ultraviolet photodetectors.…”

Section: Introductionmentioning

confidence: 99%

Lattice Instability and Ultralow Lattice Thermal Conductivity of Layered PbIF

Yedukondalu

Shafique

Roshan

et al. 2022

ACS Appl. Mater. Interfaces

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Understanding the interplay between various design strategies (for instance, bonding heterogeneity and lone pair induced anharmonicity) to achieve ultralow lattice thermal conductivity (κ l ) is indispensable for discovering novel functional materials for thermal energy applications. In the present study, we investigate layered PbXF (X = Cl, Br, I), which offers bonding heterogeneity through the layered crystal structure, anharmonicity through the Pb 2+ 6s 2 lone pair, and phonon softening through the mass difference between F and Pb/X. The weak inter-layer van der Waals bonding and the strong intra-layer ionic bonding with partial covalent bonding result in a significant bonding heterogeneity and a poor phonon transport in the out-of-plane direction.Large average Grüneisen parameters (≥ 2.5) demonstrate strong anharmonicity. The computed phonon dispersions show flat bands, which suggest short phonon lifetimes, especially for PbIF. Enhanced Born effective charges are due to cross-band-gap hybridization. PbIF shows lattice instability at a small volume expansion of 0.1%. The κ l values obtained by the two channel transport model are 20-50% higher than those obtained by solving the Boltzmann transport equation. Overall, ultralow κ l values are found at 300 K, especially for PbIF. We propose that the interplay of bonding heterogeneity, lone pair induced anharmonicity, and constituent elements with high mass difference aids the design of low κ l materials for thermal energy applications.

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Section: Introductionmentioning

confidence: 99%

Lattice Instability and Ultralow Lattice Thermal Conductivity of Layered PbIF

Yedukondalu

Shafique

Roshan

et al. 2022

ACS Appl. Mater. Interfaces

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“…Alkaline-earth haloflourides MXF (M= Ca, Sr, Ba and X = Cl, Br, I) belong to the layered PbClF-type (Matlockite) family that crystallize in the primitive tetragonal crystal symmetry ( P 4/ nmm ; Z = 2) at ambient conditions. , Recently, PbClF-type materials have been receiving considerable interest as two-dimensional (2D) materials due to their layered crystal structures and have found potential applications in supercapacitors nano- and optoelectronic devices. − When these materials are doped with di- or trivalent rare-earth metals, they exhibit strong photo-stimulated luminescence (PSL); therefore, they can serve as storage image phosphors for measuring X-ray dosage . Sm 2+ -doped SrClF can be used as a luminescence sensor and also for spectral-hole burning at room temperature .…”

Section: Introductionmentioning

confidence: 99%

Pressure-Induced Martensitic Phase Transition and Low Lattice Thermal Conductivity of SrClF

et al. 2021

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In the present work, we report a pressure-induced martensitic phase transition for SrClF, which is analogous to BaClF and PbClF compounds. The predicted structural phase transition sequence for SrClF below 200 GPa is as follows: P4/nmm → Pmcn → P63/mmc with an increase in the coordination of a metal cation with structural motifs MCl5F4 [9] → MCl6F4 [10] → MCl6F5 [11], where M = Sr, Ba, and Pb, respectively. The martensitic phase transition is mainly driven by the cooperative displacive nature of M, Cl, and F atoms, which removes lattice distortion from the austenite (Pmcn) phase under pressure. Anharmonic lattice dynamics and thermal conductivity (k l) are calculated using the temperature-dependent effective potential (TDEP) method. Dynamical stability of the predicted high-pressure phases is confirmed from the computed phonon dispersion curves and density of states at 300 K. Short phonon lifetimes and low group velocities of acoustic modes of CaClF and SrClF are attributed to their low k l values along with their quasi-two-dimensional (2D) layered structures.

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“…The structure is built from ionically bonded X–M–F–F–M–X layers that are stacked along the c -axis and bound to each other by ionic or weak vdW forces (Figure b). These materials have attracted tremendous attention because of their unique electronic properties and promising applications such as energy storage, photodetectors, and optoelectronic devices. − Barhoumi et al have studied the electronic and vibrational properties of the BaBrF, CaBrF, and BaClF monolayers. Tan et al have shown that the band gaps of lead dihalides increase from 2.3 eV (PbI 2 ) to 5.8 eV (PbF 2 ), which are the ideal wide band gap semiconductors to develop UV photodetectors.…”

Section: Introductionmentioning

confidence: 99%

Highly Anisotropic to Isotropic Nature and Ultralow Out-of-Plane Lattice Thermal Conductivity of Layered PbClF-Type Materials

Rakesh Roshan,

Yedukondalu,

Rajaboina

et al. 2024

Inorg. Chem.

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Materials with an extreme lattice thermal conductivity (κ l ) are indispensable for thermal energy management applications. Layered materials provide an avenue for designing such functional materials due to their intrinsic bonding heterogeneity. Therefore, a microscopic understanding of the crystal structure, bonding, anharmonic lattice dynamics, and phonon transport properties is critically important for layered materials. Alkaline-earth halofluorides exhibit anisotropy from their layered crystal structure, which is strongly determined by axial bond(s), and it is attributed to the large axial ratio (c/a > 2) for CaBrF, CaIF, and SrIF, in which Br/I acts as a rattler, as evidenced from potential energy curves and phonon density of states. The low axial (c/a) ratio leads to relatively isotropic κ l values in the BaXF (X = Cl, Br, I) series. MXF (M = Ca, Sr, Ba) compounds exhibit highly anisotropic (a large phonon transport anisotropy ratio of 10.95 for CaIF) to isotropic (a small phonon transport anisotropy ratio of 1.49 for BaBrF) κ l values despite their iso-structure. Moreover, ultralow κ l (<1 W/m K) values have been predicted for CaBrF, CaIF, and SrIF in the out-of-plane direction due to weak van der Waals (vdWs) bonding. Overall, this comprehensive study on MXF compounds provides insights into designing low κ l layered materials with a large axial ratio by fine-tuning out-of-plane bonding from ionic to vdWs bonding.

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A study of two-dimensional PbFCl and BaFCl

Cited by 6 publications

References 26 publications

Lattice Instability and Ultralow Lattice Thermal Conductivity of Layered PbIF

Lattice Instability and Ultralow Lattice Thermal Conductivity of Layered PbIF

Pressure-Induced Martensitic Phase Transition and Low Lattice Thermal Conductivity of SrClF

Highly Anisotropic to Isotropic Nature and Ultralow Out-of-Plane Lattice Thermal Conductivity of Layered PbClF-Type Materials

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