Lattice Dynamics of Incommensurate Composite Rb-IV and a Realization of the Monatomic Linear Chain Model

Loa, I.; Lundegaard, L. F.; McMahon, M. I.; Evans, Shaun R.; Bossak, A.; Krisch, M.

doi:10.1103/physrevlett.99.035501

Cited by 19 publications

(15 citation statements)

References 25 publications

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“…Experiments by Loa et al between 16.3 and 18.4 GPa observed two well-defined longitudinal acoustic phonon branches along the c axis direction, corresponding to separate oscillations from the host lattice and guest chains [34]. They found the measured sound velocity of the guest chain oscillations could be well predicted by treating the guest atoms as a linear monatomic chain suggesting that the "melting" is due to loss of order between chains.…”

Section: Introductionmentioning

confidence: 81%

“…It means that there are four zero-or near-zero-frequency phonons at the point, the usual three acoustic modes from the host lattice, plus a fourth mode, the phason mode, in which the guest chains slide rigidly along the chain direction relative to the host framework. At finite wave vectors along the chain direction, there are two longitudinal acoustic phonon branches: one with the periodicity of the host and the other with that of the guest [34].…”

Section: Enthalpies and Structuresmentioning

confidence: 99%

“…Inspired by the work of Loa et al [34] the guest phonon branch in Rb-IV was treated as a linear chain along the c axis. [34].…”

Section: Enthalpies and Structuresmentioning

confidence: 99%

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Structural and electronic properties of the alkali metal incommensurate phases

Woolman

Robinson

Marqués

et al. 2018

Phys. Rev. Materials

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Under pressure, the alkali elements sodium, potassium, and rubidium adopt nonperiodic structures based on two incommensurate interpenetrating lattices. While all elements form the same "host" lattice, their "guest" lattices are all distinct. The physical mechanism that stabilizes these phases is not known, and detailed calculations are challenging due to the incommensurability of the lattices. Using a series of commensurate approximant structures, we tackle this issue using density functional theory calculations. In Na and K, the calculations prove accurate enough to reproduce not only the stability of the host-guest phases, but also the complicated pressure dependence of the host-guest ratio and the two guest-lattice transitions. We find Rb-IV to be metastable at all pressures, and suggest it is a high-temperature phase. The electronic structure of these materials is unique: they exhibit two distinct, coexisting types of electride behavior, with both fully localized pseudoanions and electrons localized in 1D wells in the host lattice, leading to low conductivity. While all phases feature pseudogaps in the electronic density of states, the perturbative free-electron picture applies to Na, but not to K and Rb, due to significant d-orbital population in the latter.

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Section: Introductionmentioning

confidence: 81%

Section: Enthalpies and Structuresmentioning

confidence: 99%

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Structural and electronic properties of the alkali metal incommensurate phases

Woolman

Robinson

Marqués

et al. 2018

Phys. Rev. Materials

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“…Two rather different slopes were observed in Bi 2 Sr 2 CuO [43]. In the "self-hosting" composite, where the same atom is implicated both in the host and in the guest matrix, it is quite naturally the same slope which is measured around (hkl0) and (hk0m) Bragg peaks [44]. In the high symmetry phase of Hg 3− AsF 6 , the mercury presents a one dimensional liquid-like character to which are associated scattering plane perpendicular to the incommensurate direction (in this case, actually two orthogonal directions).…”

Section: Dynamics In Aperiodic Compositesmentioning

confidence: 93%

Crystallography and dynamics in superspace

et al. 2017

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Abstract. The discovery in materials of long range order without lattice periodicity has generated a very broad field of research with the introduction of totally new concepts. The common feature of this new state of matter is the translational symmetry recovered by adding supplementary dimensions to the physical space, defining a crystallographic superspace. Along these supplementary directions, specific low excitations, so-called phasons, are predicted and observed. These quasi-periodic crystals may present phase transitions as function of external parameters, which have then to be described as symmetry breakings within these crystallographic superspaces. Three different families of quasi-periodic crystals are usually considered: incommensurate modulated crystals, aperiodic composites and quasicrystals. Their crystallography and dynamics are discussed.

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“…In general, they undergo phase transitions under pressure to denser phases with more close-packed structures and increasing atomic coordination, except alkaline and alkaline-earth elements due to the promotion of s-and p-electrons to d-orbitals with increasing pressure [52,53]; however, due to the considerable differences of the electronic configurations in the different elements very different high-pressure phases including complex incommensurately modulated and incommensurate host-guest composite structures have been discovered in the last two decades. It is worth mentioning that despite considerable progress has been recently made in determining the crystal structures of the complex high-pressure structures [54], little is known about their physical properties [55]. In fact, an unexplored area for searching a charge-density wave state competing with the superconducting state in many complex incommensurate crystal structures of group V, VI, and VII heavy elements has been recently devised [56].…”

Section: Elements Under Pressurementioning

confidence: 99%

Pressure‐induced structural phase transitions in materials and earth sciences

Manjón

Errandonea

2008

Physica Status Solidi (b)

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Pressure is an important thermodynamic parameter since it allows an increase of matter density by reducing volume. The reduction of volume by applying high pressures leads to an overall decrease of interatomic and intermolecular distances that allows exploring in detail atomic and molecular interactions. Therefore, high‐pressure research has improved our fundamental understanding of these interactions in solids, liquids and gasses. The study of the structure of matter under compression is a rapid developing field that is receiving increasing attention especially due to continuous experimental and theoretical developments. In this article, we give a brief description of the experimental and theoretical methods employed in the study of solid matter at high pressures and summarize the high‐pressure phases of the most relevant elements and inorganic compounds of the AX, A2X, AX2, ABX2, A2X3, ABX3, ABX4 and AB2X4 families giving an overview of the state of the art in high‐pressure research by highlighting recent discoveries, hot spots, controversial questions, and future directions of research. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Lattice Dynamics of Incommensurate Composite Rb-IV and a Realization of the Monatomic Linear Chain Model

Cited by 19 publications

References 25 publications

Structural and electronic properties of the alkali metal incommensurate phases

Structural and electronic properties of the alkali metal incommensurate phases

Crystallography and dynamics in superspace

Pressure‐induced structural phase transitions in materials and earth sciences

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