Sökning: "Garnet"

Visar resultat 1 - 5 av 41 avhandlingar innehållade ordet Garnet.

1. 1. 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

3. 2. Bismuth iron garnet films for magneto-optical photonic crystals

   Författare :Sören Kahl; KTH; []
   Nyckelord :Faraday effect; iron garnet; pulsed laser deposition; photonic crystals;

   Sammanfattning : The thesis explores preparation and properties of bismuthiron garnet (BIG) films and the incorporation of BIG films intoone-dimensional magneto-optical photonic crystals (MOPCs). Films were prepared by pulsed laser deposition. LÄS MER

4. 3. Materials for High-Temperature Catalytic Combustion

   Författare :Anders Ersson; KTH; []
   Nyckelord :catalytic combustion; catalyst materials; palladium; platinum; bimetallic; garnet; spinel; hexaaluminate; deactivation; sulphur; poisoning; diesel; methane; hydrocarbons;

   Sammanfattning : Catalytic combustion is an environmentally friendlytechnique to combust fuels in e.g. gas turbines. Introducing acatalyst into the combustion chamber of a gas turbine allowscombustion outside the normal flammability limits. LÄS MER

5. 4. Catalytic combustion of gasified waste

   Författare :Henrik Kusar; KTH; []
   Nyckelord :Catalytic combustion; Gasified waste; LHV-fuel; RDF; Biomass; Selective catalytic oxidation; NH3; NOX; Palladium; Platinum; Hexaaluminate; Garnet; Spinel; Deactivation; Sulphur; Poisoning;

   Sammanfattning : This thesis concerns catalytic combustion for gas turbineapplication using a low heating-value (LHV) gas, derived fromgasified waste. The main research in catalytic combustionfocuses on methane as fuel, but an increasing interest isdirected towards catalytic combustion of LHV fuels. LÄS MER

7. 5. 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