Sökning: "Phonons"

Visar resultat 1 - 5 av 36 avhandlingar innehållade ordet Phonons.

  1. 1. Time-resolved X-ray diffraction studies of phonons and phase transitions

    Detta är en avhandling från Department of Physics, Lund University

    Författare :Ola Synnergren; Lunds universitet.; Lund University.; Malmö University.; [2005]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysik; Physics; Phase transitions; X-ray diffraction; Phonons; phonons; phase transitions;

    Sammanfattning : Popular Abstract in Swedish Denna avhandling sammanfattar arbete där tidsupplöst röntgendiffraktion har använts för att undersöka kristallina material och studera dynamiken hos fononer och fasövergångar. Röntgendiffraktion är standardverktyget för stukturbestämning på en atomär skala. LÄS MER

  2. 2. Significance of grain boundaries for transport phenomena in graphene and proton-conducting barium zirconate

    Detta är en avhandling från Department of Physics, Lund University

    Författare :Edit Ahlberg Helgee; [2015]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; graphene; density functional theory; phonons; proton conduction; grain boundaries; BaZrO3; interatomic model potentials;

    Sammanfattning : Grain boundaries can have a significant influence on the properties of polycrystalline materials. When determining the type and extent of this influence it is frequently useful to employ computational methods such as density functional theory and molecular dynamics, which can provide models of the grain boundary structure at the atomistic level. LÄS MER

  3. 3. Time-resolved x-ray diffraction of nanostructured samples

    Detta är en avhandling från Department of Physics, Lund University

    Författare :A. I. H. Persson; Lunds universitet.; Lund University.; [2016]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; x-ray diffraction; phonons; optoacoustic transducer; electron diffusion; nanowires; Fysicumarkivet A:2016:Persson;

    Sammanfattning : The work presented in this thesis is based on time-resolved x-ray diffraction studies of InSb (111) samples. The experiments were carried out using a pump-probe configuration using short laser pulses as the pump and x-rays as the probe. Laser excitation leads to the formation of a strain pulse that propagates through the sample. LÄS MER

  4. 4. Low-frequency noise characterization, evaluation and modeling of advanced Si- and SiGe-based CMOS transistors

    Detta är en avhandling från Stockholm : KTH

    Författare :Martin von Haartman; KTH.; [2006]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; MOSFET; SOI; SiGe; strain; high-k; metal gate; 1 f noise; low-frequency noise; mobility fluctuations; phonons; number fluctuations; traps; buried channel; mobility; substrate bias; TECHNOLOGY Electrical engineering; electronics and photonics Electronics; TEKNIKVETENSKAP Elektroteknik; elektronik och fotonik Elektronik;

    Sammanfattning : A wide variety of novel complementary-metal-oxide-semiconductor (CMOS) devices that are strong contenders for future high-speed and low-noise RF circuits have been evaluated by means of static electrical measurements and low-frequency noise characterizations in this thesis. These novel field-effect transistors (FETs) include (i) compressively strained SiGe channel pMOSFETs, (ii) tensile strained Si nMOSFETs, (iii) MOSFETs with high-k gate dielectrics, (iv) metal gate and (v) silicon-on-insulator (SOI) devices. LÄS MER

  5. 5. Effects of disorder in metallic systems from First-Principles calculations

    Detta är en avhandling från Linköping : Linköping University Electronic Press

    Författare :Christian Asker; Linköpings universitet.; Linköpings universitet.; [2010]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Iron; Nickel; Magnesium; Manganese; Molybdenum; Zirconium; Elastic Constants; High pressure; Earth s core; Density-functional theory; Ab-initio; First-Principles; Core-level shifts; Molecular Dynamics; Phonons; Dynamical Instability; NATURAL SCIENCES Physics Condensed matter physics; NATURVETENSKAP Fysik Kondenserade materiens fysik; NATURAL SCIENCES Physics Other physics Computational physics; NATURVETENSKAP Fysik Övrig fysik Beräkningsfysik;

    Sammanfattning : In this thesis, quantum-mechanical calculations within density-functional theory on metallic systems are presented. The overarching goal has been to investigate effects of disorder. In particular, one of the properties investigated is the bindingenergy shifts for core electrons in binary alloys using different theoretical methods. LÄS MER