PhD Position in Physics
University of Antwerp
Belgium

The University of Antwerp is a dynamic, forward-thinking, European university. We offer innovative academic education to more than 20000 students, conduct pioneering scientific research and play an important service-providing role in society. We are one of the largest, most international and most innovative employers in the Antwerp region. With more than 6000 employees from 100 different countries, we are helping to build tomorrow's world every day. Through top scientific research, we push back boundaries and set a course for the future – a future that you can help to shape. 

In the framework of the NANOLight Center of Excellence of the University of Antwerp, the AXIS research group (Faculty of Science) in collaboration with the Environmental Economics (EnvEcon) research group (Faculty of Business and Economics) is seeking to fill one full-time (100%) doctoral scholarship holder (PhD) position in the area of “Light-induced Reactivity and Redox Transformations of Minium (Pb₃O₄, red lead)” under the supervision of Prof Koen Janssens (U. Antwerp, Belgium) together with Prof. Steven Van Passel (U. Antwerp, Belgium) and Dr. Marine Cotte (European Synchrotron Radiation Facility, Grenoble, France).

Lead (Pb) compounds of various types, colors and mechanical properties have been mined, refined and synthesized in all historical periods from antiquity to the present day. These include(d) metallic lead, oxides and various salts of lead. The lead battery, still used in many cars worldwide, is an example of how the redox properties of lead can be exploited to advance human technology and society in a sustainable manner. When a lead battery is (dis)charged, in a controlled manner, electrons are attached or detached from Pb⁰, Pb²⁺ or Pb⁴⁺, hereby converting chemical into electric power or vice versa. However, the anodic and cathodic half-reactions governing these transformations can also occur in a non-controlled manner, for example when light impinges on lead-containing materials. In some contexts (e.g. perovskite-based solar cells) this is exploited for the intentional conversion of (solar) light into electrical power; however, in many other situations, unwanted photo-corrosion of the lead-containing materials can occur. Such a context is that of lead-containing (artistic or industrial) paints that may significantly change their color and mechanical strength as a result of light-induced redox reactions of the lead compounds present in the paint.

A reactive lead oxide of major interest is the mixed valence oxide minium (Pb₃O₄ or 2Pb(+II)O.Pb(+IV)O₂), aka as red lead. While less reactive in pure form, its reactivity is expected to increase markedly when an excess of PbO (litharge or massicot) is present in the solid material as an impurity. The latter may be the result of incomplete or imperfectly executed minium synthesis procedures. When exposed to organic molecules such as lipids, red minium may remove some electrons from these molecules, causing them to oxidize. The electrons convert Pb(+IV)- into Pb(+II)-ions that together with fatty acids may form colorless/transparent lead soaps (i.e., lead carboxylates) that take up a significantly higher volume that the original minium. In some conditions, also lead formates and carbonates may be formed. In this PhD project, the spontaneous degradation of minium under the influence of various physicochemical environmental factors will be studied.

In the context of museum sustainability, minimizing the degradation of lead-based pigments through innovative conservation practices is essential for preserving cultural heritage in a responsible manner. By developing discrete choice experiments to assess the public’s willingness to pay for environmentally friendly art conservation methods—such as those based on nanoscience—can help align preservation strategies with societal values and environmental goals. These insights can also support the further development of innovative, more environmental-friendly, technologies.

Topic

With the aim of answering research questions such as:

• In which conditions does minium form lead soaps/lead carbonates? Is the resulting mixture of secondary lead compounds similar for minium and for PbO? Which half-reactions are taking place in the presence/absence of environmental factors such as light, moisture and specific paint binding media?
• Can the reactivity of minium be completely attributed to an excess of PbO in case of absence or presence of activation by light? How essential is the latter for minium to react with reduced biomolecules such as lipids and fatty acids?
• Under which circumstances (pCO₂) is the formation of lead carbonates favoured over that of (large and small) lead carboxylates?
• What is the willingness of museum visitors to pay for environmentally friendly art conservation methods (in order to minimize spontaneous degradation phenomena)?

you will undertake the following activities:

• systematically synthesize minium based on existing recipes, hereby varying the excess of PbO
• expose these minium variants to light of various wavelength, to various types of oils (= lipid sources) for different time durations to allow spontaneously formation of secondary lead products (= in vitro reactivity study);
• analyze the resulting complex solid mixtures using sophisticated X-ray based and electron microscopy based methods;
• analyze paint microsamples collected from historical paintings of different periods in which minium was used in order to critically compare the effects of long term in situ short term in vitro reactivity of minimum.

In addition to this main topic, you will also collect information and develop insights regarding the sustainability of museum management in the context of spontaneously occurring reactions of pigmented materials. Discrete Choice Experiments (DCEs), a (survey-based) method to elicit public preferences for goods and services, will be undertaken. While DCE have found widespread use in health, transport and environmental economics, their specific application to the field of art conservation is still to be made: most existing DCE literature in museum settings focusses on visitor preferences re. admission fees, opening hours or art collection type. Concretely, you will investigate the visitors' willingness to enable environmentally friendly art conservation by nanoscience via (slightly elevated) museum ticket prices. This novel application will provide valuable insights into preferences of visitors and the intersection of art preservation and environmental concerns.

Research groups involved

AXIS is a research group specializing in the use of X-ray beams for non-invasive imaging analysis of materials at different length scale. A special interest of AXIS is the reactivity of artists’ pigments in different historical periods (15^th-19^th century). AXIS has a 30-year long history of collaboration with the European Synchrotron Radiation Facility, a state-of-the art research institute for X-ray based material characterization in Grenoble, France. EnvEcon is a research group focused on sustainability by exploring the interactions between the environment and the economy. The team members of EnvEcon explore how technoligical innovations, value chain transformations, and changes in societal behavior can effectively tackle sustainability.

Position

• You will work actively on the preparation and defence of a PhD thesis in the field of Sciences.
• You will publish scientific articles related to the research project.
• You will present your work at national and international workshops and conferences.

Profile

• PhD position: You hold a Master’s degree with background in e.g. chemistry, (applied) physics, or materials science.
• You can demonstrate excellent study results.
• Your research qualities are in line with the faculty and university research policies.
• You act with attention to quality, integrity, creativity and cooperation.
• You are enthusiastic and greatly interested in electron microscopy.
• You can submit outstanding academic results.
• You are highly motivated, quality-oriented, conscientious, creative and cooperative.
• You have affinity with experimental work and show good practical skills
• You are greatly interested in the (quantitative) analysis and interpretation of chemical imaging data sets containing information on chemical transformations in heterogenous systems.
• You show interest in sustainability and are open to learn basic socio-economic analysis.

What we offer

• A doctoral scholarship for a period of 4 year, the first year being considered as a trial period. Following a positive evaluation after 1 year, the scholarship will be extended with 3 years.
• Place of work: University of Antwerp (BE), ESRF (Grenoble, FR) and possibly other facilities.
• An exciting project in which we will aim to go significantly beyond the state-of-the-art.
• The preferred start date is as soon as possible but will be adapted to the selected candidate’s availability.
• Your monthly scholarship amount is calculated according to the scholarship amounts for doctoral scholarship holders on the pay scales for Contract Research Staff (Dutch: Bijzonder Academisch Personeel, BAP).
• You will have the opportunity to be immersed in a world-class, dynamic and stimulating work environment with state-of-the-art instrumentation and computing facilities.
• Find out more about working at the University of Antwerp here.

Want to apply?

• You can apply for this vacancy through the University of Antwerp’s online job application platform up to and including September 3^rd 20235 (by midnight Brussels time). Click on the 'Apply' button, complete the online application form and be sure to include the following attachments:
• a motivation letter,
• your academic CV (including followed courses, honours, previous work, programming skills, publications, …)
• a list and grades of the courses from that you took during your studies (Bachelor and Master)
• contact info of 2 professional reference persons
• The selection committee will review all of the applications as soon as possible after the application deadline. As soon as a decision has been made, we will inform you about the next steps in the selection procedure.
• If you have any questions about the online application form, please check the frequently asked questions or send an email to jobs@uantwerpen.be. If you have any questions about the job itself, please contact Prof. Koen Janssens, janssens@uantwerpen.be.

The University of Antwerp received the European Commission’s HR Excellence in Research Award for its HR policy. We are a sustainable, family-friendly organisation which invests in its employees’ growth. We encourage diversity and attach great importance to an inclusive working environment and equal opportunities, regardless of gender identity, disability, race, ethnicity, religion or belief, sexual orientation or age. We encourage people from diverse backgrounds and with diverse characteristics to apply.