Search Results (94)
Charge compensation mechanisms and twinning in doped SnO2-based ceramics
Tin (IV) oxide, SnO2 (cassiterite), is an n-type semiconductor with an advantageous combination of chemical, electric and optical properties that make it suitable for a range of applications, from solid-state gas sensors, transparent conductive coatings, oxidation catalysts and varistors. In varistor ceramics, grain growth studies are of particular interest, because …
Surfaces and interfaces in the growth of SrTiO3 on Si by pulsed laser deposition
SrTiO3 (STO) thin films are used as buffer layers that enable epitaxial integration of various functional oxides with silicon. When pulsed laser deposition (PLD) is used to grow STO on Si, a thin amorphous layer is formed at the STO-Si interface that limits the use of such heterostructures in certain …
Correlation of the mechanical properties and wear behaviour with the microstructural characteristics of tool steels
Wear is one of the key problems with many types of engineering components as it can limit their life expectancy. The same is true for tools and tool steels, which are the focus of this doctoral thesis. Tool-wear response and behaviour are closely related to a material’s final microstructure and …
Vacuum metrology and the role of surface conditions on the tangential momentum accommodation of molecules in a rarefied gas
The interactions between gas molecules and a surface strongly affect the behaviour of systems in a large array of research fields, such as vacuum science and metrology, microfluidics, particle physics, and nuclear physics. In this work, focus is given to the momentum accommodation of gas molecules. The parameter used in …
Defect chemistry and hardening of ferroelectric cobalt-doped bismuth ferrite ceramics: doctoral thesis
Bismuth ferrite, BiFeO3 (BFO), has been recognized as a promising lead-free material for high-temperature piezoelectric applications due to its high Curie temperature of 825 °C. However, the practical use of BFO has been limited in particular by its elevated electrical conductivity. In addition, BFO shows the characteristics of ferroelectric hardening, …
CO2 dynamics in a river system: mass balance, hydrological, geochemical and biochemical impacts
A 3-year systematic investigation (2007–2010) of water chemistry using conventional and stable isotope tracers helped us delineate hydro-biogeochemical processes in the karstic Krka River watershed. By mineralogical and stable isotopic examination of tufa deposits and combining the results with water chemistry, we were able to evaluate the suitability of tufa …
Organic geochemistry of stratified eutrophic alpine lakes (Lake Bled)
The identification and quantification of organic compounds present in the environment is a major area of application in modern analytical chemistry. However, it is still scarcely recognized that, in addition to the chemical identity and concentration of organic compounds, there is more information to be found about their source and …
Development of SiC-based composite material for fusion application
Nuclear fusion offers a prospect of a safe, economical and environmentally friendly source of energy. For the advanced concepts of nuclear fusion, SiC-based fibre reinforced composites were proposed as a structural material for the first wall of the reactor vessel, enabling higher operating temperatures and efficiencies. Already developed techniques for …
Sintering and phase transition behaviour of sodium niobate
Sodium niobate (NaNbO3) is the end member of several alkaline niobate-based solid solutions, which represent an important group of environment-friendly lead-free piezoceramics. Even though alkaline niobates are of considerable technological importance, problems in obtaining high densities and a fine-grained microstructure are still reported and not much is known about the …
Laser Ablation - Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) - Fundamental Study of Ablation and Deposition Processes
Laser ablation (LA) is a versatile technique that can be used for the elemental analysis of diverse materials as well as for synthesis purposes, i.e. for pulsed laser deposition (PLD) of a wide range of materials. Analysis and synthesis will only be successful if the ablated material can be stoichiometrically …