Sökning: "Quasicrystals"

Visar resultat 1 - 5 av 18 avhandlingar innehållade ordet Quasicrystals.

  1. 1. Frustrated magnetism in icosahedral structures : The influence of order-disorder in quasicrystals and approximant crystals

    Författare :Fernand Denoel; Roland Mathieu; Marc de Boissieu; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; quasicrystals; approximant crystals; spin glasses; SQUID magnetometry; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : This work will begin with an introduction to quasicrystals (QCs) and their structure, defining the unit cell-equivalent for icosahedral quasiperiodicity: a 3D tiling based on the golden ratio and aperiodic in all three dimensions. We briefly present the cut-and-project method used to generate QCs from a higher dimension hypercrystal, and how to build the 3D Penrose tilings, composed of the two golden rhombohedra. LÄS MER

  3. 2. Calorimetry under extreme conditions

    Författare :Neha Kondedan; Andreas Rydh; Ali Elshaari; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nanocalorimetry; Diamond anvil cell; Specific heat; Thermometry; Quasicrystals; Solid State Physics; fasta tillståndets fysik;

    Sammanfattning : This licentiate thesis presents developments of nanocalorimetry systems tailored for use under extreme conditions such as high pressure, intense magnetic fields, and low temperature. Nanocalorimetry is a powerful approach to study strongly correlated systems like superconductors, heavy fermions, and quantum materials with non-trivial magnetic or electronic properties, materials with emergent magnetic orders, as well as quasicrystals. LÄS MER

  4. 3. Syntheses, structure determination, magnetic and thermoelectric properties of quasicrystal approximants in RE-Au-SM systems (RE = Gd, Tb and Yb and SM = Si, Ge)

    Författare :Girma Hailu Gebresenbut; Cesar Gomez; Martin Sahlberg; Torbjörn Gustafsson; Lars Eriksson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Quasicrystals; quasicrystal approximants; thermoelectric properties; magnetic properties; Materialvetenskap; Materials Science;

    Sammanfattning : In this study, new compositions of Tsai-type 1/1 quasicrystal approximants Gd(14)Au(70)Si(16), Gd(14)Au(67)Ge(19), Tb(14)Au(70)Si(16) and Yb(16)Au(65)Ge(19)are synthesized using both self-flux and arc-melting-annealing techniques. Both syntheses routes resulted single phase samples. LÄS MER

  5. 4. Computer Simulations of Simple Liquids with Tetrahedral Local Order : the Supercooled Liquid, Solids and Phase Transitions

    Författare :Måns Elenius; Mikhail Dzugutov; Jonathan Doye; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Simple liquids; glasses; liquid-glass transition; supercooled liquids; tetrahedral liquids; phase transitions; quasicrystals; molecular dynamics; Condensed matter physics; Kondenserade materiens fysik; Liquid physics; Vätskefysik; numerisk analys; Numerical Analysis;

    Sammanfattning : The understanding of complex condensed matter systems is an area of intense study. In this thesis, some properties of simple liquids with strong preference for tetrahedral local ordering are explored. These liquids are amenable to supercooling, and give complex crystalline structures on eventual crystallisation. LÄS MER

  7. 5. Spectra and Dynamics of Excitations in Long-Range Correlated Structures

    Författare :Lars Kroon; Rolf Riklund; Magnus Johansson; Jeroen Lamb; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quasicrystals; deterministic aperiodic superlattices; Markov chains; electronic structure and diffusion; elastic vibrations; Fraunhofer diffraction; discrete solitons; phase transitions; Condensed matter physics; Kondenserade materiens fysik;

    Sammanfattning : Vad karaktäriserar en kristall? Svaret på denna till synes enkla fråga blir kanske att det är en anordning av atomer uppradade i periodiska mönster. Så ordnade strukturer kan studeras genom att det uppträder så kallade Braggtoppar i röntgendiffraktionsmönstret. LÄS MER