Pressure-induced crossing of the core levels in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>5</mml:mn><mml:mi>d</mml:mi></mml:mrow></mml:math>metals

Tal, Alexey A.; Katsnelson, M. I.; Ekholm, Marcus; Jönsson, H. Johan M.; Dubrovinsky, Leonid; Abrikosov, Igor A.

doi:10.1103/physrevb.93.205150

Cited by 14 publications

(10 citation statements)

References 36 publications

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“…On the other hand, Re presents a negative slope in the c/a evolution between ambient and 150 GPa 17 . This behaviour is probably caused by a recently discovered electronic transition called Core-Level Crossing (CLC) 1 . In this transition, the pressure-induced crossing of the deep 5p and 4f levels affects the valence electrons and hence the chemical bonds in the metal.…”

Section: Resultsmentioning

confidence: 99%

“…Transition metals have always attracted the interest of the scientific community due to their unusual electronic and structural properties, originating from the dominant influence of their d electrons. Often, they exhibit pronounced phonon anomalies as a result of complex Fermi-surface geometries coupled with strong electron-phonon interactions 1,2 . For these reasons, in the past decades big effort has been devoted to map and interpret the systematic properties of this metals at both ambient and extreme conditions of pressure and temperature 3 .…”

Section: Introductionmentioning

confidence: 99%

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Thermal equation of state of ruthenium characterized by resistively heated diamond anvil cell

Anzellini

Errandonea

Cazorla

et al. 2019

Sci Rep

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The high-pressure and high-temperature structural and chemical stability of ruthenium has been investigated via synchrotron X-ray diffraction using a resistively heated diamond anvil cell. In the present experiment, ruthenium remains stable in the hcp phase up to 150 GPa and 960 K. The thermal equation of state has been determined based upon the data collected following four different isotherms. A quasi-hydrostatic equation of state at ambient temperature has also been characterized up to 150 GPa. The measured equation of state and structural parameters have been compared to the results of ab initio simulations performed with several exchange-correlation functionals. The agreement between theory and experiments is generally quite good. Phonon calculations were also carried out to show that hcp ruthenium is not only structurally but also dynamically stable up to extreme pressures. These calculations also allow the pressure dependence of the Raman-active E2g mode and the silent B1g mode of Ru to be determined.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal equation of state of ruthenium characterized by resistively heated diamond anvil cell

Anzellini

Errandonea

Cazorla

et al. 2019

Sci Rep

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“…When pressure increases, the Ba 5d bands broaden and mix with the Ba 6s bands, which is comparable to the s → d transition observed in elemental alkaline earth metals. 59 These Ba s−d hybridized states overlap with the occupied N 2p states of isolated N 3− anions, conferring conductivity to C2/c Ba 3 N 2 at high pressure, regardless of the weak density of states at the Fermi level.…”

Section: Resultsmentioning

confidence: 99%

Barium–Nitrogen Phases Under Pressure: Emergence of Structural Diversity and Nitrogen-Rich Compounds

Huang

Frapper

2018

Chem. Mater.

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Although the potential of polynitrogen as a high-energy density material (HEDM) has attracted attention, the difficulty of preserving polynitrogen thwarts attempts to discover molecular and extended nitrogen structures. Mixing nitrogen with electropositive elements to obtain viable solid-state compounds represents one approach to overcome thermodynamic/kinetic instability. In pursuit of barium nitrides within the Ba–N family, we theoretically explored the ground/metastable structures from ambient pressure up to 100 GPa. Crystal structure prediction (CSP) based on evolutionary algorithms and density functional theory identified 13 stoichiometries and 24 stable structures; several metastable phases were dynamically stable. Pressure and barium/nitrogen ratio represent controllable factors for polynitrogen net preparation. Four types of phases could be classified based on nitrogen structural dimensionality: isolated nitrogen atom; nitrogen molecules, e.g., N2 dumbbells, linear N3 azides, N4 zigzag units, N5 pentazolate, N6 six-membered rings; 1D polythiazyl S2N2-like nitrogen chains; and 2D polymeric nitrogen layers. Interestingly, P63/mcm-Ba3N, R3̅m-Ba2N, and C2/m-Ba3N2 have predicted electride properties. Notably, we observe electronic property changes in the charge-balanced Ba3N2 compound as pressure increases. Solid-state Ba3N2 changes from a conducting electride at ambient pressure with encapsulated anionic N2 dumbbells and isolated N atoms to a nitride semiconductor above 5 GPa in which isolated N3– ions are trapped within a Ba2+ oceanas expected for textbook charge-balanced structuresand is metallic above 25 GPa. In addition, ab initio molecular dynamics analysis indicates nitrogen-rich BaN2, BaN4, and bis-pentazolate Ba(N5)2 are quenchable to ambient pressure, suggesting these polymeric nitrogen networks can be preserved up to at least 600 K; these quenchable phases are promising candidate HEDMs.

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“…This pressure-induced transition has been associated with interactions between the core electrons that affect the pressure evolution of the lattice parameter ratio c/a in Os at 440 GPa. In a methodical theoretical of the CLC transition reported the prediction of a generality of the effect in 5d transition metals 11 , revealing a CLC transition for Ir at a reasonable low-pressure of 80 GPa. Such a prediction makes Ir a great candidate for the study of its pressure-induced evolution of the electronic structure, in which the 5p and 4 f core electrons at the CLC transition could affect the valence electrons due to the nonlocal nature of the electron interactions.…”

Section: Introductionmentioning

confidence: 99%

Phase stability and electronic structure of iridium metal at the megabar range

Monteseguro

Sans

Cuartero

et al. 2019

Sci Rep

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The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed to exhibit a recently discovered pressure-induced electronic transition, the so-called core-level crossing transition at the lowest pressure among all the 5d transition metals. Here, we report an experimental structural characterization of iridium by x-ray probes sensitive to both long- and short-range order in matter. Synchrotron-based powder x-ray diffraction results highlight a large stability range (up to 1.4 Mbar) of the low-pressure phase. The compressibility behaviour was characterized by an accurate determination of the pressure-volume equation of state, with a bulk modulus of 339(3) GPa and its derivative of 5.3(1). X-ray absorption spectroscopy, which probes the local structure and the empty density of electronic states above the Fermi level, was also utilized. The remarkable agreement observed between experimental and calculated spectra validates the reliability of theoretical predictions of the pressure dependence of the electronic structure of iridium in the studied interval of compressions.

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Pressure-induced crossing of the core levels in5dmetals

Cited by 14 publications

References 36 publications

Thermal equation of state of ruthenium characterized by resistively heated diamond anvil cell

Thermal equation of state of ruthenium characterized by resistively heated diamond anvil cell

Barium–Nitrogen Phases Under Pressure: Emergence of Structural Diversity and Nitrogen-Rich Compounds

Phase stability and electronic structure of iridium metal at the megabar range

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