First-principles study of the lattice dynamics, thermodynamic properties and electron-phonon coupling of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Y</mml:mi><mml:msub><mml:mi mathvariant="normal">B</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math>

Xu, Ying; Zhang, Lijun; Cui, Tian; Li, Yan; Xie, Yu; Yu, Wen; Ma, Yanming; Zou, Guangtian

doi:10.1103/physrevb.76.214103

Cited by 46 publications

(27 citation statements)

References 49 publications

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“…Experimental and theoretical values of lattice constants and bulk moduli for defect-free structures compare well for Ca, Sr, Ba, Eu, Yb, Y, La and Cd hex-aborides [34]. Experimental data from NMR analysis [37] of YB 6 is also strongly supported by theoretical calculations of band structure, density of states and valenceelectron distributions. Estimates for z, the boron 6f position shows good correlation [34,40] for YB 6 , BaB 6 and ThB 6 .…”

Section: Stoichiometrysupporting

confidence: 54%

“…Valence state also influences these properties as divalent hexaborides are commonly insulators or semiconductors and trivalent hexaborides are commonly metallic [5,33,37]. As noted earlier, KB 6 is identified as not a "normal" metal [12] and ThB 6 is a paramagnetic metal [13].…”

Section: Electronic Structuresmentioning

confidence: 95%

“…Theoretical calculations of elastic, electronic and lattice dynamic parameters for metal hexaboride structures are ultimately constrained by geometry or crystal structure [33,34,37]. Valence state also influences these properties as divalent hexaborides are commonly insulators or semiconductors and trivalent hexaborides are commonly metallic [5,33,37].…”

Section: Electronic Structuresmentioning

confidence: 99%

“…Very small concentrations of defects influence electronic properties in structures with small, or no apparent, band gap [37]. For example, in CaB 6 the presence of boron-related defects (the difference between 6N and 3N purity or << 1%) are closely associated with carrier doping and the formation of mid-gap states 0.18 eV below the conduction band [5].…”

Section: Stoichiometrymentioning

confidence: 99%

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Metal Hexaborides with Sc, Ti or Mn

Alarco¹,

Talbot²

2013

MNSMS

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Comparison of well-determined single crystal data for stoichiometric, or near-stoichiometric, metal hexaborides confirms previously identified lattice parameter trends using powder diffraction. Trends for both divalent and trivalent forms suggest that potential new forms for synthesis include Sc and Mn hexaborides. Density Functional Theory (DFT) calculations for KB 6 , CaB 6 , YB 6 , LaB 6 , boron octahedral clusters and Sc and Mn forms show that the shapes of bonding orbitals are defined by the boron framework. Inclusion of metal into the boron framework induces a reduction in energy ranging from 1 eV to 6 eV increasing with ionic charge. For metals with d 1 character, such a shift in energy brings a doubly degenerate band section along with the G-M reciprocal space direction within the conduction bands tangential to the Fermi surface. ScB 6 band structure and density of states calculations show directions and gap characteristics similar to those of YB 6 and LaB 6 . These calculations for ScB 6 suggest that it may be possible to realize superconductivity in this compound if synthesized.

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Section: Stoichiometrysupporting

confidence: 54%

Section: Electronic Structuresmentioning

confidence: 95%

Section: Electronic Structuresmentioning

confidence: 99%

Section: Stoichiometrymentioning

confidence: 99%

See 2 more Smart Citations

Metal Hexaborides with Sc, Ti or Mn

Alarco¹,

Talbot²

2013

MNSMS

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“…Experimental evidence for a change in phonon frequencies in Zn was found by inelastic neutron scattering at a pressure of approximately 6.8 GPa [362], but the effect on elastic constants has been questioned [370]. An enhanced EPI after an electronic topological transition under pressure was recently reported in theoretical work on YB 6 [371].…”

Section: Kohn Anomalies and Electronic Topological Transitionsmentioning

confidence: 96%

Vibrational thermodynamics of materials

Fultz¹

2010

Progress in Materials Science

558

428

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Abstract. The literature on vibrational thermodynamics of materials is reviewed. The emphasis is on metals and alloys, especially on the progress over the last decade in understanding differences in the vibrational entropy of different alloy phases and phase transformations. Some results on carbides, nitrides, oxides, hydrides and lithium-storage materials are also covered.Principles of harmonic phonons in alloys are organized into thermodynamic models for unmixing and ordering transformations on an Ising lattice, and extended for non-harmonic potentials. Owing to the high accuracy required for the phonon frequencies, quantitative predictions of vibrational entropy with analytical models prove elusive. Accurate tools for such calculations or measurements were challenging for many years, but are more accessible today. Ab-initio methods for calculating phonons in solids are summarized. The experimental techniques of calorimetry, inelastic neutron scattering, and inelastic x-ray scattering are explained with enough detail to show the issues of using these methods for investigations of vibrational thermodynamics. The explanations extend to methods of data analysis that affect the accuracy of thermodynamic information.It is sometimes possible to identify the structural and chemical origins of the differences in vibrational entropy of materials, and the number of these assessments is growing. There has been considerable progress in our understanding of the vibrational entropy of mixing in solid solutions, compound formation from pure elements, chemical unmixing of alloys, order-disorder transformations, and martensitic transformations. Systematic trends are available for some of these phase transformations, although more examples are needed, and many results are less reliable at high temperatures. Nanostructures in materials can alter sufficiently the vibrational dynamics to affect thermodynamic stability. Internal stresses in polycrystals of anisotropic materials also contribute to the heat capacity. Lanthanides and actinides show a complex interplay of vibrational, electronic, and magnetic entropy, even at low temperatures.A "quasiharmonic model" is often used to extend the systematics of harmonic phonons to high temperatures by accounting for the effects of thermal expansion against a bulk modulus. Non-harmonic effects beyond the quasiharmonic approximation originate from the interactions of thermally-excited phonons with other phonons, or with the interactions of phonons with electronic excitations. In the classical high temperature limit, the adiabatic electron-phonon coupling can have a surprisingly large effect in metals when temperature causes significant changes in the electron density near the Fermi level. There are useful similarities in how temperature, pressure, and composition alter the conduction electron screening and the interatomic force constants. Phononphonon "anharmonic" interactions arise from those non-harmonic parts of the interatomic potential that cannot be accounted for by the quasiharmonic ...

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Anti-adiabatic State: Ground Electronic State of Superconductors

Baňacký

2011

Advances in the Theory of Quantum Systems in Chemistry and Physics

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First-principles study of the lattice dynamics, thermodynamic properties and electron-phonon coupling ofYB6

Cited by 46 publications

References 49 publications

Metal Hexaborides with Sc, Ti or Mn

Metal Hexaborides with Sc, Ti or Mn

Vibrational thermodynamics of materials

Anti-adiabatic State: Ground Electronic State of Superconductors

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