Degree projects

(Only in Swedish)
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

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

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

Aromatic organic compounds are widely applied in areas such as pharmaceuticals, pesticides, herbicides, flame retardants, plasticizer, and cosmetics. They are usually very stable due to the resonance stabilization and can therefore remain in the environment for very long times. Some of these (e.g. PFAS) have been called “forever chemicals” due to their resistance to degradation.

Many of these aromatic compounds have been found to have negative effects on both plant and animal health. For example, both bisphenols (particularly bisphenol A) and perfluoroalkyl substances (PFAS) are endocrine disruptors. Discharge of sublethal amounts of antibiotics are resulting in increased antibiotic resistance. Aromatics containing hydrophilic functions (e.g. OH, COOH) are easily spread by surface waters, and can even find their way to ground waters. A multitude of volatile organic compounds (VOC) are released from furniture and home appliances and can cause the so-called sick building syndrome. These includes diverse such as aromatic aldehydes and benzene.

Hence, there is a strong incentive to efficiently remove these compounds from both water and air. Advanced oxidation processes (AOP) which include photocatalysis, electrocatalysis, and Fenton process, are among the most popular methods for degrading organic pollutants. They are based on the generations of different reactive oxygen species, most importantly OH● radicals, to stepwise degrade the pollutants. A properly optimized system can completely degrade any organic compound to water and carbon dioxide. However, the delocalization of electrons in aromatic compounds renders them less reactive and therefore more complicated to quickly degrade. There further risk going through a series of hydroxylated/oxygenated aromatic intermediates of even higher toxicity.

A proton insertion, breaking the aromaticity, could facilitate ring-opening and thereby the degradation and possibly by-pass or reduce the series of oxygenated aromatic intermediates. An ordinary acid is not strong enough to protonate aromatics, but super acids are.

Our recent work with solid super acid photocatalysts has suggested a proton-mediated double bond cleavage mechanism. The purpose of this project is to systematically investigate the reactions of a few simple aromatic compounds by solid super acids, both in dark and under UV-illumination. This will mainly be performed by operando FTIR studies (gas phase) where different intermediates and reaction products can be discerned. The effect of reaction temperatures will also be considered. 2D correlation spectrometry can assist the identification of different reaction sequences between reaction conditions. Finally, intermediates/reaction products of the most promising reaction conditions will be collected and analyzed by 1H NMR, and possibly GC/MS.

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