keyword
MENU ▼
Read by QxMD icon Read
search

quasicrystals

keyword
https://www.readbyqxmd.com/read/28530242/interface-driven-formation-of-a-two-dimensional-dodecagonal-fullerene-quasicrystal
#1
M Paßens, V Caciuc, N Atodiresei, M Feuerbacher, M Moors, R E Dunin-Borkowski, S Blügel, R Waser, S Karthäuser
Since their discovery, quasicrystals have attracted continuous research interest due to their unique structural and physical properties. Recently, it was demonstrated that dodecagonal quasicrystals could be used as bandgap materials in next-generation photonic devices. However, a full understanding of the formation mechanism of quasicrystals is necessary to control their physical properties. Here we report the formation of a two-dimensional dodecagonal fullerene quasicrystal on a Pt3Ti(111) surface, which can be described in terms of a square-triangle tiling...
May 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28487537/evidence-of-cross-cutting-and-redox-reaction-in-khatyrka-meteorite-reveals-metallic-al-minerals-formed-in-outer-space
#2
Chaney Lin, Lincoln S Hollister, Glenn J MacPherson, Luca Bindi, Chi Ma, Christopher L Andronicos, Paul J Steinhardt
We report on a fragment of the quasicrystal-bearing CV3 carbonaceous chondrite Khatyrka recovered from fine-grained, clay-rich sediments in the Koryak Mountains, Chukotka (Russia). We show higher melting-point silicate glass cross-cutting lower melting-point Al-Cu-Fe alloys, as well as unambiguous evidence of a reduction-oxidation reaction history between Al-Cu-Fe alloys and silicate melt. The redox reactions involve reduction of FeO and SiO2 to Fe and Fe-Si metal, and oxidation of metallic Al to Al2O3, occurring where silicate melt was in contact with Al-Cu-Fe alloys...
May 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28442721/near-field-surface-plasmons-on-quasicrystal-metasurfaces
#3
Quanlong Yang, Xueqian Zhang, Shaoxian Li, Quan Xu, Ranjan Singh, Yongmin Liu, Yanfeng Li, Sergey S Kruk, Jianqiang Gu, Jiaguang Han, Weili Zhang
Excitation and manipulation of surface plasmons (SPs) are essential in developing cutting-edge plasmonic devices for medical diagnostics, biochemical spectroscopy and communications. The most common approach involves designing an array of periodic slits or grating apertures that enables coupling of the incident light to the SP modes. In recent years, plasmonic resonances, including extraordinary optical transmission through periodic arrays, quasicrystals and random aperture arrays, have been investigated in the free space...
December 23, 2016: Scientific Reports
https://www.readbyqxmd.com/read/28417127/on-the-formation-of-stripe-sigma-and-honeycomb-phases-in-a-core-corona-system
#4
Harini Pattabhiraman, Marjolein Dijkstra
Using Monte Carlo simulations and free-energy calculations, we investigate the phase behaviour of a two-dimensional core-corona system. We model this system as particles consisting of an impenetrable hard core of diameter σHD surrounded by a purely repulsive soft corona of diameter δ = 1.95σHD. At low densities, we observe the spontaneous formation of a phase with a stripe texture as well as a honeycomb-like phase driven by both energy and entropy considerations. At high densities, we find that a two-dimensional analogue of the periodic sigma phase, considered as an approximant of dodecagonal quasicrystals, is energetically stabilised with respect to two distinct dodecagonal quasicrystals, namely, a square-triangle tiling and a square-triangle-shield tiling...
April 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28401877/non-close-packed-three-dimensional-quasicrystals
#5
Pablo Damasceno, Sharon Glotzer, Michael Engel
Quasicrystals are frequently encountered in condensed matter. They are important candidates for equilibrium phases from the atomic scale to the nanoscale. Here, we investigate the computational self-assembly of four quasicrystals in a single model system of identical particles interacting with a tunable isotropic pair potential. We reproduce a known icosahedral quasicrystal and report a decagonal quasicrystal, a dodecagonal quasicrystal, and an octagonal quasicrystal. The quasicrystals have low coordination number or occur in systems with mesoscale density variations...
April 12, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28358719/properties-of-quasiperiodic-functions
#6
Johannes Roth
Today, quasiperiodic tilings are well known and have been studied in great detail since they are very useful to describe the properties of metallic and soft matter quasicrystals. A closely related topic are quasiperiodic functions which have also gained large interest recently. Different types of such functions and there interrelation will be presented here. The main topic will be quasiperiodic potentials generated by laser beams and their variability. The distribution of extremal points and local isomorphisms of quasiperiodic functions will also be addressed...
March 30, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28345537/hyperuniformity-variation-with-quasicrystal-local-isomorphism-class
#7
C Lin, P J Steinhardt, S Torquato
Hyperuniformity is the suppression of long-wavelength density fluctuations, relative to typical structurally disordered systems. In this paper, we examine how the degree of hyperuniformity [[Formula: see text]] in quasicrystals depends on the local isomorphism class. By studying the continuum of pentagonal quasicrystal tilings obtained by direct projection from a five-dimensional hypercubic lattice, we find that [Formula: see text] is dominantly determined by the local distribution of vertex environments (e...
May 24, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28330366/phase-behaviour-of-quasicrystal-forming-systems-of-core-corona-particles
#8
Harini Pattabhiraman, Marjolein Dijkstra
Using Monte Carlo simulations and free-energy calculations, we study the phase behaviour of a two-dimensional system of particles interacting with a hard core of diameter σHD and a repulsive square shoulder potential. The interest in this system lies in the formation of quasicrystals of different symmetries at specific square-shoulder widths δ as previously reported by Dotera et al. [Nature 506, 208 (2014)]. However, an insight into other possible periodic phases formed in these systems and the thermodynamic stability of both the periodic and quasicrystal phases is yet to be addressed...
March 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28248662/b7-as-a-supergroup-of-crystal-and-quasicrystal-symmetries
#9
Kazimierz Stróż
In sharp contrast to the generation of a finite group that includes all the 14 types of Bravais lattices as its subgroups [Hosoya (2000). Acta Cryst. A56, 259-263; Hosoya (2002). Acta Cryst. A58, 208], it was proved that a signed permutation group Bk may be interpreted as the supergroup of both crystal and quasicrystal symmetries. Minimal dimension k = 6 is adequate for lattices referred to their three non-coplanar shortest vectors, or for symmetry groups of most quasicrystal types. If one prefers complete, well defined semi-reduced lattice descriptions or needs a dodecagonal group, the B7 supergroup is necessary...
March 1, 2017: Acta Crystallographica. Section A, Foundations and Advances
https://www.readbyqxmd.com/read/28140368/observation-of-a-dodecagonal-oxide-quasicrystal-and-its-complex-approximant-in-the-srtio3-pt-1%C3%A2-1%C3%A2-1-system
#10
Sebastian Schenk, Stefan Förster, Klaus Meinel, René Hammer, Bettina Leibundgut, Maximilian Paleschke, Jonas Pantzer, Christoph Dresler, Florian O Schumann, Wolf Widdra
We report on the formation of a SrTiO3-derived dodecagonal oxide quasicrystal (OQC) at the interface to Pt(1 1 1). This is the second observation of a two-dimensional quasicrystal in the class of oxides. The SrTiO3-derived OQC exhibits strong similarities to the BaTiO3-derived OQC with respect to the local tiling geometry. However, the characteristic length scale of the SrTiO3-derived OQC is 1.8% smaller. Coexisting with the OQC a large scale approximant structure with a monoclinic unit cell is identified...
January 31, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28106533/defect-structures-in-frank-kasper-type-square-triangle-tiling-of-multimodal-cage-type-mesoporous-silicas
#11
Yasuhiro Sakamoto
Multimodal cage-type mesoporous silicas (MCMSs) with Frank-Kasper type square-triangle tiling show a unique defect structure, so-called three-fold symmetric hexagons, or shields, which are caused by phason fluctuations in dodecagonal quasicrystals. We observed and characterized three types of configurations inside shields in both quasiperiodic and periodic 3(2).4.3.4 tiling of MCMSs by transmission electron microscopy (TEM). The high-resolution TEM images of the shields were well explained by polyhedral models, which are the constituents of the Frank-Kasper type tetrahedrally close-packed structures of MCMSs...
March 29, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28072393/stability-of-icosahedral-quasicrystals-in-a-simple-model-with-two-length-scales
#12
Kai Jiang, Pingwen Zhang, An-Chang Shi
The phase behaviour of a free energy functional with two length scales is examined by comparing the free energy of different candidate phases including three-dimensional icosahedral quasicrystals. Accurate free energy of the quasicrystals has been obtained using the recently developed projection method. The results reveal that the icosahedral quasicrystal and body-centred-cubic spherical phase are the stable ordered phases of the model. Furthermore, the difference between the results obtained from the projection method and the one-mode approximation has been analyzed in detail...
March 29, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28008870/detection-of-phonon-and-phason-modes-in-intrinsic-colloidal-quasicrystals-by-reconstructing-their-structure-in-hyperspace
#13
J Hielscher, M Martinsons, M Schmiedeberg, S C Kapfer
Phasons are additional degrees of freedom which occur in quasicrystals alongside the phonons known from conventional periodic crystals. The rearrangements of particles that are associated with a phason mode are hard to interpret in physical space. We reconstruct the quasicrystal structure by an embedding into extended higher-dimensional space, where phasons correspond to displacements perpendicular to the physical space. In dislocation-free decagonal colloidal quasicrystals annealed with Brownian dynamics simulations, we identify thermal phonon and phason modes...
March 8, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28003663/near-field-surface-plasmons-on-quasicrystal-metasurfaces
#14
Quanlong Yang, Xueqian Zhang, Shaoxian Li, Quan Xu, Ranjan Singh, Yongmin Liu, Yanfeng Li, Sergey S Kruk, Jianqiang Gu, Jiaguang Han, Weili Zhang
Excitation and manipulation of surface plasmons (SPs) are essential in developing cutting-edge plasmonic devices for medical diagnostics, biochemical spectroscopy and communications. The most common approach involves designing an array of periodic slits or grating apertures that enables coupling of the incident light to the SP modes. In recent years, plasmonic resonances, including extraordinary optical transmission through periodic arrays, quasicrystals and random aperture arrays, have been investigated in the free space...
December 2016: Scientific Reports
https://www.readbyqxmd.com/read/28001131/the-effect-of-temperature-interaction-range-and-pair-potential-on-the-formation-of-dodecagonal-quasicrystals-in-core-corona-systems
#15
Harini Pattabhiraman, Marjolein Dijkstra
A two-dimensional dodecagonal quasicrystal was previously reported by Dotera et al (2014 Nature 506 208) in a system of particles interacting with a hard core of diameter σ and a repulsive square shoulder of diameter [Formula: see text]. In the current work, we examine the formation of this quasicrystal using bond orientational order parameters, correlation functions and tiling distributions. We find that this dodecagonal quasicrystal forms from a fluid phase. We further study the effect of the width of the repulsive shoulder by simulating the system over a range of values of δ...
March 8, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/27980514/pushing-the-limits-of-crystallography
#16
Janusz Wolny, Ireneusz Buganski, Pawel Kuczera, Radoslaw Strzalka
A very serious concern of scientists dealing with crystal structure refinement, including theoretical research, pertains to the characteristic bias in calculated versus measured diffraction intensities, observed particularly in the weak reflection regime. This bias is here attributed to corrective factors for phonons and, even more distinctly, phasons, and credible proof supporting this assumption is given. The lack of a consistent theory of phasons in quasicrystals significantly contributes to this characteristic bias...
December 1, 2016: Journal of Applied Crystallography
https://www.readbyqxmd.com/read/27973520/multimode-photon-exciton-coupling-in-an-organic-dye-attached-photonic-quasicrystal
#17
Kun Zhang, Yue Xu, Tian-Yong Chen, Hao Jing, Wen-Bo Shi, Bo Xiong, Ru-Wen Peng, Mu Wang
In this Letter, we present hybrid strong coupling between multiple photonic modes and excitons in an organic-dye-attached photonic quasicrystal. The excitons effectively interact with the photonic modes offered by the photonic quasicrystal, and multiple hybrid polariton bands are demonstrated in both experiments and calculations. Furthermore, by retrieving the measured dispersion map, we get the mixing fractions of photonic modes and excitons, and show that the polariton bands inherit not only the energy dispersion features, but also the damping behaviors from both the photonic modes and the excitons...
December 15, 2016: Optics Letters
https://www.readbyqxmd.com/read/27941869/deterministic-composite-nanophotonic-lattices-in-large-area-for-broadband-applications
#18
Jolly Xavier, Jürgen Probst, Christiane Becker
Exotic manipulation of the flow of photons in nanoengineered materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced broadband photonic and plasmonic technologies for spectrally tailorable integrated biosensing, nanostructured thin film solarcells, white light emitting diodes, novel plasmonic ensembles etc. Through a generic deterministic nanotechnological route here we show subwavelength-scale silicon (Si) nanostructures on nanoimprinted glass substrate in large area (4 cm(2)) with advanced functional features of aperiodic composite nanophotonic lattices...
December 12, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27929519/collisions-in-outer-space-produced-an-icosahedral-phase-in-the-khatyrka-meteorite-never-observed-previously-in-the-laboratory
#19
Luca Bindi, Chaney Lin, Chi Ma, Paul J Steinhardt
We report the first occurrence of an icosahedral quasicrystal with composition Al62.0(8)Cu31.2(8)Fe6.8(4), outside the measured equilibrium stability field at standard pressure of the previously reported Al-Cu-Fe quasicrystal (AlxCuyFez, with x between 61 and 64, y between 24 and 26, z between 12 and 13%). The new icosahedral mineral formed naturally and was discovered in the Khatyrka meteorite, a recently described CV3 carbonaceous chondrite that experienced shock metamorphism, local melting (with conditions exceeding 5 GPa and 1,200 °C in some locations), and rapid cooling, all of which likely resulted from impact-induced shock in space...
December 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27911786/geometry-induced-sequence-of-nanoscale-frank-kasper-and-quasicrystal-mesophases-in-giant-surfactants
#20
Kan Yue, Mingjun Huang, Ryan L Marson, Jinlin He, Jiahao Huang, Zhe Zhou, Jing Wang, Chang Liu, Xuesheng Yan, Kan Wu, Zaihong Guo, Hao Liu, Wei Zhang, Peihong Ni, Chrys Wesdemiotis, Wen-Bin Zhang, Sharon C Glotzer, Stephen Z D Cheng
Frank-Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails...
December 13, 2016: Proceedings of the National Academy of Sciences of the United States of America
keyword
keyword
113842
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"