Sökning: "High current densities"

Visar resultat 1 - 5 av 104 avhandlingar innehållade orden High current densities.

1. 1. From Current Collectors to Electrodes : Aluminium Rod Structures for Three-dimensional Li-ion Micro-battery Applications

   Författare :Gabriel Oltean; Kristina Edström; Leif Nyholm; Erik Kelder; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; 3D micro-batteries; aluminium; titanium oxide; current collectros; negative electrodes; electrodepostion; electrophoretic depostion; sol-gel synthesis;

   Sammanfattning : The potential use of 3D aluminium nanorod structures as current collectors and negative electrodes for 3D Li-ion micro-batteries was studied based on the use of relatively simple and cost-effective electrochemical and sol-gel deposition techniques.Aluminium rod structures were synthesised by galvanostatic electrodeposition using commercial porous membranes as templates. LÄS MER

3. 2. Phase transitions in high-temperature superconductors

   Författare :Jack Lidmar; KTH; []
   Nyckelord :Superconductivity; Vortices; Phase transitions; Strongly correlated fermions; High-temperature superconductivity; Monte Carlo simulations.; TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : Thermal fluctuations and disorder strongly influence the behaviour of hightemperature superconductors. In particular the vortices play a key role in determining their properties. In this thesis the main focus lies on phase transitions, both in ultra-thin films and in three-dimensional systems, which are driven by vortex fluctuations. LÄS MER

4. 3. High power bipolar junction transistors in silicon carbide

   Författare :Hyung-Seok Lee; Carl-Mikael Zetterling; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Silicon Carbide SiC ; power device; biplar junction transistor; TiW; ohmic contact; current gain; Electronics; Elektronik;

   Sammanfattning : As a power device material, SiC has gained remarkable attention to its high thermal conductivity and high breakdown electric field. SiC bipolar junction transistors (BJTs) are interesting for applications as power switch for 600 V-1200 V applications. LÄS MER

5. 4. Fundamentals of High Power Impulse Magnetron Sputtering

   Författare :Johan Böhlmark; Ulf Helmersson; André Anders; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Plasma; Pulsed plasma; High Power Pulsed Magnetron Sputtering; Plasma Characterization; Physics; Fysik;

   Sammanfattning : In plasma assisted thin film growth, control over the energy and direction of the incoming species is desired. If the growth species are ionized this can be achieved by the use of a substrate bias or a magnetic field. Ions may be accelerated by an applied potential, whereas neutral particles may not. LÄS MER

7. 5. YBCO nanowires to study nanoscale ordering in High-Tc Superconductors

   Författare :Riccardo Arpaia; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; nanoscale ordering; nanoSQUIDs; nanowires; High-Tc superconductors; ultrathin films; oxygen doping; nanowire-based single photon detectors;

   Sammanfattning : We present the realization of YBa2Cu3O7-δ (YBCO) nanowires for both basic physics studies, which could help to elucidate the microscopic mechanisms of High critical Temperature Superconductors (HTS), and for novel applications.The first part of the thesis describes an improved nanopatterning procedure, based on e-beam lithography in combination with an amorphous carbon mask and a very gentle Ar+ ion etching. LÄS MER