Sökning: "high-temperature phase transitions"

Visar resultat 21 - 25 av 25 avhandlingar innehållade orden high-temperature phase transitions.

1. 21. Magnetic and Structural Properties of f-electron Systems from First Principles Theory

   Författare :Torbjörn Björkman; Olle Eriksson; Thomas Schulthess; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik; Materialvetenskap; Materials Science;

   Sammanfattning : A series of studies of f-electron systems based on density functional theory methods have been performed.  The focus of the studies has been on magnetic and structural properties, as well as investigating ways to handle strong electron correlation in these systems. LÄS MER

3. 22. Thermoelectric Properties of Antimony Based Networks

   Författare :Andreas Tengå; Sven Lidin; Michael Ruck; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; thermoelectric; narrow gap semiconductors; zinc antimonides; cadmium antimonides; chalcopyrites; sphalerites; Inorganic chemistry; Oorganisk kemi; Materials Chemistry; materialkemi;

   Sammanfattning : With the retreating sources of carbon based fuels, thermoelectric materials can play an important role in the future of environmentally friendly power generators. Sb based framework have in some cases shown some promising properties as thermoelectric materials. The physical properties may be modified with doping or incorporation of new elements. LÄS MER

4. 23. Effects of Strong Correlations in Complex Oxides Investigated by Raman Spectroscopy

   Författare :Joakim Holmlund; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Our global environment is under excessive strain and we are facing a possible global climate change. There is a urgent need today for finding both alternative energy sources and new techniques for the transport and storage of energy in order to save our planet in its present status. LÄS MER

5. 24. Theoretical Studies of Magnetism and Electron Correlation in Solids

   Författare :Oscar Grånäs; Lars Nordström; Biplab Sanyal; Silke Biermann; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetism; Superconductivity; Electron Correlation; DMFT; DFT; Actinides; multipoles; hidden order; magnetic anisotropy; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : This work presents new development and applications of ab-initio simulation tools for material science. Focus lies on materials with strong electronic correlation and strong spin-orbit coupling. LÄS MER

7. 25. Quasicrystal Approximants in the RE-Au-SM systems (RE = Gd, Tb, Ho, Yb; SM = Si, Ge) : Syntheses, structures and properties

   Författare :Girma Hailu Gebresenbut; Cesar Pay Gómez; Martin Sahlberg; Torbjörn Gustafsson; Alan I. Goldman; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Quasicrystal approximant; structure; physical property; Chemistry with specialization in Inorganic Chemistry; Kemi med inriktning mot oorganisk kemi; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : In this study, new Tsai-type 1/1 quasicrystal approximants (ACs) in the RE-Au-SM systems (RE = Gd, Tb, Ho, Yb; SM = Si, Ge) were synthesized using high temperature synthesis techniques such as self-flux, arc-melting-annealing and novel arc-melting-self-flux methods. The syntheses not only provided appropriate samples for the intended structural and physical property measurements but could also be adapted to other systems, especially where crystal growth is a challenge. LÄS MER