Degree project

We welcome you to contact us if you are interested in doing your degree project with us. Sometimes we have project proposals to give but there is usually something to do. You can read about our research areas and projects and see what may interest you. Contact any of our researchers if you are interested. 

Bakgrund

Spectrogon AB ett helsvenskt, familjeägt, optikföretag beläget i Täby (norr om Stockholm) som utvecklar, tillverkar och säljer tunnfilms- och gitterprodukter inom våglängdsområdet ultraviolett till infrarött.

Optiska filter är en kritisk del i optiska instrument. Optiska index för de material som används till långvågiga IR-filter är temperaturberoende och påverkar filtrets funktion. Att känna till de ingående materials beteende vid låga temperaturer blir då avgörande för den slutliga funktionen. Användningsområden där filter utnyttjas vid låga temperaturer finns bland annat i rymd-tillämpningar och för instrument som med hög precision använder termisk IR.

Företaget har genom åren levererat filter som nu är monterade i flera rymdprojekt såsom t ex James Webb Space Telescope för NASA och Rosetta för ESA. Dessa projekt har haft som mål att öka förståelsen för universums födelse (Webb) och analys av material på komet (Rosetta). Spectrogon har även levererat filter till satelliter för miljöövervakning.

Spectrogon önskar med detta examensarbete öka sin förståelse, och förbättra sina beräkningsmodeller, för att även i fortsättningen kunna leverera högkvalitativa optiska komponenter.

Projektbeskrivning

I projektet undersöks hur brytningsindex, n, för dielektriska beläggningar som Germanium ändras som funktion av temperatur, T; speciellt kryogeniska temperaturer ner till 4 K, dvs dn/dT. Inom optiken är det av central betydelse att förstå och kvantifiera denna förändring. Det är känt att t.ex. laseruppvärmning leder till en ökning (dn/dT > 0), vilket leder till en ”själv-fokusering” av ljuset som kan skada optiska komponenter. Andra effekter är ljusspridning i fasta kroppar som påverkas genom lokal uppvärmning och densitetsvariationer. Den fysikaliska anledningen till förändringen av brytningsindex beror på en temperatur-inducerad förändring av den lokala densiteten i materialet. Denna kan t.ex. modelleras med s.k. oscillatormodeller (Lorentz-Lorentz och Drude). I projektet ska vi ta fram data och analytiska uttryck för dn/dT och prediktera förändringen av brytningsindex vid kryogeniska temperaturer för att antal beläggningar som är relevanta i industriella tillämpningar. Företaget Spectrogon tillhandahåller materialdata och ger en praktisk bakgrund till den industriella tillämpningen. Spectrogon önskar att merparten av arbetet sker på plats vid företagets huvudkontor i Arninge, Täby.

Projektet handleds av Dr. José Montero och Prof. Lars Österlund vid Adv. Fasta tillståndets fysik, Inst. materialvetenskap vid Uppsala universitet. Bihandledare är Tomas Landström och Herman Högström på Spectrogon AB.

Kontakt

Lars Österlund, Professor, Adv. Fasta tillståndets fysik, Uppsala universitet, lars.osterlund@angstrom.uu.se, Phone: 0702-562425

Herman Högström COO Spectrogon AB, herman.hogstrom@spectrogon.com,

Phone: +46-(0)73-6870046

Introduction

Environmental pollutants are increasing in the environment, both water and air, due to human activities. These includes organic compounds such as pesticides, antibiotics, flame retardants, volatile organic compounds (VOCs) and can have negative impact on animal and plant welfare. Metal oxide based photocatalysis has emerged as a promising strategy to remediate polluted water and air. Illumination of the metal oxides generates reactive oxygen species (ROS) and electron holes which are strongly oxidizing and can decompose organic compounds into water and carbon dioxide. One of the major obstacles in employing photocatalysis is fast electron-hole recombination which limits the amount of ROS and holes available for reaction. Combination of n-type and p-type metal oxides can be utilized to form p-n junction which facilitates the electron-hole separation. Here, the two metal oxides must be in close contact.

Another issue in photocatalysis, particularly in the gas phase, is build up of reaction intermediates that strongly coordinate to active sites and decrease the efficiency (e.g. surface poisoning). Surface acidification has demonstrated to slow down the build-up of deactivating reaction products and thereby increasing the life time of the photocatalyst. The surface acidification also results in hydrophobicity of the surface, which is interesting for self-cleaning coatings. Here, the wetting properties (e.g. contact angles, superhydrophilicity/superhydrophobicity) is of interest.      

Project description

The proposed project consists of two parts, one dealing with the development of a new CuO-ZnO heterojunction photocatalyst. This includes synthesis and characterization of physical properties and photocatalytic properties. CuO will be deposited on ZnO “nanoflowers” in a two-step reaction. Wet chemical methods (e.g. solution synthesis, hydrothermal synthesis) will be employed to produce the materials. The materials will be characterized by techniques such as powder X-ray diffraction, elemental analysis (EDS, XRF), scanning electron microscopy (SEM), UV-vis, and FITR spectroscopy. Photocatalytic activities will be investigated by relevant model compounds.

Studies of wetting properties concerns mainly titanium dioxide (TiO₂) surface functionalized with sulfate groups. Contact angle measurements for water will be done to determine surface properties, with some subsequent modelling. Self-cleaning properties will be investigated by the retention of fatty substances on the surface.

Both sub-projects are part of ongoing research and successful work can be included in future publications. The candidate should have a background in chemistry/materials science.

Contact

Prof. Lars Österlund, lars.osterlund@angstrom.uu.se
Dr. Fredric Svensson, fredric.svensson@angstrom.uu.se
Division of Solid-State Physics, Department of Materials Science and Engineering, Uppsala University

Background:

Glass as a material has the ability to contribute to the solution of several societal challenges that we are facing today. More glass than ever is used in buildings because of the transparency of glass, which lets sunlight into buildings and increases human well-being. Glass has also gained increased use through displays and solar energy, while glass packaging loses its market share to plastics, mainly because it is a heavier material. Glass is energy-intensive to manufacture and in order to manufacture thinner glass products, the glass needs to be made stronger. Chemical strengthening of glass is an old invention but has relatively recently achieved proper commercial success. However, the understanding of chemical strengthening is still not complete in several aspects, due to the complexity of the process and its mechanisms. Through a better understanding of the mechanisms, the possibilities of improving chemical strengthening of glass will be opened up.

Project Description:

The glass composition affects chemical strengthening a great deal since it is based on interdiffusion of larger ions from a molten salt bath into the glass and smaller ions out of the glass. Chemical strengthening is based on two different processes, the kinetic that is connected to the interdiffusion and the physical processes that turns the “stuffing” of ions into compressive stress which can be separated into two relaxation processes 1) structural relaxation and 2) viscous relaxation. In the current project we wish to study the structural information of chemically strengthened glass in relation to the concentration profiles using XPS. The interdiffusion coefficient will be calculated as well as the activation energy and an attempt to simulate the compressive stress build-up will be made.

The thesis will be jointly supervised by Uppsala University and RISE Glass, located in Växjö. The work will involve literature review and characterization of glasses. The majority of the work will be performed at the division of Solid State Physics, Department of Engineering Sciences, Uppsala University. RISE will provide glass samples to be measured at the Ångström Laboratory, Uppsala University. Good knowledge of physics and/or chemistry is mandatory.

RISE Research Institutes of Sweden
Building Technology – Glass                                             

Contact person:
RISE
Stefan Karlsson
Building Technology
+46 10 516 63 57
stefan.karlsson@ri.se     

                                                                  
                                                                                                                      
 

Background:

Glass as a material has the ability to contribute to the solution of several societal challenges that we are facing today. Solar energy is one of future energy resources where glass is having an important function as a transparent cover glass. However, without being coated glass is reflecting about 8% of the incoming solar radiation. Today low-iron glass with anti-reflective (AR) coating is typically used and this also transmits UV radiation which is energetic and therefore induces degradation of materials in photovoltaic modules (PV). Therefore are transparent UV-protective agents added to the glass, however if this is done in the coating it is possible to make the coating photocatalytic and thereby enhancing the cleanability of the PV module. However, a better understanding between solar radiation, conversion efficiency, heat generation and the cut-off wavelength of UV is needed in order to make optimized PV modules.

Project Description:

The project involves modelling of the heat generation from the solar transmittance of different UV-protective antireflective (AR) coatings in order to find an optimum based as a trade-off between heat, degradation of materials over time and efficiency. The thesis also involves some manufacturing using PVD or CVD and characterization of UV-protective AR coatings. The characterization mainly involves angle-dependent UV-Vis-NIR spectrophotometry but may involve other spectroscopic techniques as well.

The thesis will be jointly supervised by Uppsala University and RISE Glass, located in Växjö. The work will involve literature review and characterization of glasses. The majority of the work will be performed at the division of Solid State Physics, Department of Engineering Sciences, Uppsala University. RISE will provide glass samples to be measured at the Ångström Laboratory, Uppsala University. Good knowledge of physics and/or chemistry is mandatory.

RISE Research Institutes of Sweden
Materials and Surface Design – Glass                                 

Contact person:
RISE
Stefan Karlsson
Building Technology
+46 10 516 63 57
​stefan.karlsson@ri.se                                                                     
                                                                                          

A Master thesis is open in Lars Österlund’s group at the Division of Solid State Physics, Dept Materials Science and Engineering, with starting date beginning of 2023. 

We are looking for a skilled and motivated student that want to do his/her Master thesis with us in the field of materials science with specialization in optical metamaterials. Metamaterials from the Greek meta= ‘go beyond’, are a class of functional materials containing patterns or structures that cause them to interact with different external stimuli (e.g. light, heat, etc.) in unconventional ways. A photonic crystal as a particular case of a metamaterial. A photonic crystal is a material constituted by two or more materials with different refractive index arranged in a periodical fashion. In a photonic crystal light cannot propagate in the material in the usual way, and outstanding properties such as the emergence of tunable photonic band-gap appear. As a result, this type of materials can exhibit spectacular colors and iridescence. Photonic crystals are common in nature and are responsible of the coloration of some animals—e.g. iridescent colors in birds such as magpies, beetles and butterflies such as the ones belonging to the genus Morpho (Fig. 1)—and gemstones such as opals. In technological applications, photonic crystals are considered as ideal materials for e.g. light harvesting applications.

Figure 1 A Morpho butterfly (left), and a synthetic inverse opal prepared by the UU group (right).

In this Master thesis project, your task will involve simulations (computational experiment) of the optical properties of different metamaterials: inverse opals (fig. 1), and nanostructured-thin films using the Finite Difference Time Domain (FDTD) method. The FDTD method is based on the division of space and time in a grid, and solve Maxwell’s equations in each portion of that grid. For this you will rely on available computational tools. Your simulations not only will help us to design new metamaterials, but also to explain experimental data already measured in real materials in our laboratory. If successful, this work can result in publications in international peer-reviewed journals.

The thesis will be supervised by Dr. José Montero and co-supervised by Prof. Lars Österlund. The work will involve literature review, computer simulations, data analysis and scientific report writing. Good knowledge of physics, engineering physics, and/or materials chemistry is mandatory, proved e.g. by completed advanced level courses.

Contact: José Montero