Sökning: "Quenching"

Visar resultat 21 - 25 av 208 avhandlingar innehållade ordet Quenching.

1. 21. Dynamic local structural symmetries and luminescence properties of the yellow emitting phosphor Ce3+-doped Y3Al5O12

   Författare :Yuan-Chih Lin; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; free electron laser; neutron scattering; vibrational spectroscopy; phosphor; light emitting diode; luminescence; thermal quenching; garnet;

   Sammanfattning : This thesis centers on investigations of the local structure and vibrational properties of the oxide garnet Y3Al5O12 (YAG), which when substituted with a few percent of the activator ion Ce3+ to replace Y3+ (Y3−xCexAl5O12, YAG:Ce3+) is one of the most important phosphors for solid state lighting. The study builds on a comprehensive analysis of the nature of the phonons and localized vibrational modes in YAG:Ce3+ and how these depend on the Ce3+ concentration and temperature and how they affect key optical properties, such as the intensity and frequency of the emitted light. LÄS MER

3. 22. Understanding the interactions between vibrational modes and excited state relaxation in garnet structured phosphors

   Författare :Yuan-Chih Lin; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; free electron laser; thermal quenching.; luminescence; garnet; vibrational spectroscopy; neutron scattering; phosphor; light emitting diode;

   Sammanfattning : This thesis concerns investigations of the local structural environments and vibrational dynamics of the three garnet type oxide phosphors Ce3+-doped Y3Al5O12 (YAG:Ce3+), Ca3Sc2Si3O12 (CSS:Ce3+), and Sr3Y2Ge3O12 (SYG:Ce3+), which show promising optical properties as luminescent materials used in solid state white lighting technologies. The study focuses on a comprehensive analysis of the nature of the long-range vibrations (phonons) in terms of local atomic and molecular motions of the garnet structure, as well as their dependence on the nature of the garnet chemical composition, Ce3+ concentration and temperature. LÄS MER

4. 23. Ionic surfactant-polymer interactions studied by time-resolved fluorescence quenching

   Författare :Jan van Stam; Uppsala universitet; []
   Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

   Sammanfattning : .... LÄS MER

5. 24. Fatigue Anisotropy in Forged Components

   Författare :Cornelius Temmel; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Inclusion Cluster; Low Sulfur; Machinability; Inclusion; Manganese Sulfide; Quenching Crack; Forging; Isotropic Quality; Steel; Anisotropy;

   Sammanfattning : Ever-growing requirements on combustion engine efficiency of motor vehicles demand increasing service loads in powertrain components. Optimization of component material is therefore inevitable. A major detriment with many forged transmission components is their anisotropic mechanical behavior, not least during cyclic loading. LÄS MER

7. 25. Modelling of forming and quenching of ultra high strength steel components for vehicle structures

   Författare :Magnus Eriksson; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hållfasthetslära; Solid Mechanics;

   Sammanfattning : The doctoral thesis deals with modelling and simulations in integrated product and process development. The research concerns with development of models and methods for simulation of component manufacturing and product functionality. LÄS MER