The Department of Earth Sciences is now looking for a highly-motivated, high-potential applicant to fill a PhD position within the project 'CRYSTAL CLEAR: determining the impact of charge on Iron Sulfide formation'.

All of the crystals that form in water on Earth are formed through reaction between oppositely charged ions. In these crystals, the ions are present in an ideal, charge-balanced ionic ratio. In contrast, the natural solutions in which they form, contain widely diverging ionic ratios. When crystals nucleate from natural solutions, they will be charged, and charge has a massive impact on the behaviour of small new crystals. However, most nucleation experiments have been conducted in solutions with charge-balanced ionic ratios. The current PhD project encompasses state-of-the-art experiments and analyses that will provide in situ knowledge of the impact of the iron:sulfide ratio on the charge, size, growth, aggregation and transformation of iron sulfide minerals.

Anoxic marine sediment pore waters and some marine basins, such as the Black Sea, are saturated with respect to iron sulfide minerals. Pyrite is the most stable and ubiquitous iron sulfide phase in Earth-surface environments. It plays a crucial role in the global biogeochemical cycles of iron and sulfur and many trace elements. In natural environments, the ratio of iron to sulfur varies over orders of magnitude, and depends among others upon the activity of sulfur oxidizing and iron reducing bacteria.

The aim of this PhD project is to investigate the impact of the ratio of iron to sulfur on the formation of pyrite via its precursor phases. The PhD candidate will conduct iron sulfide synthesis experiments under oxygen free and sterile conditions in a glove boxed set-up. Samples will be continuously investigated by Dynamic Light Scattering and Zetapotential measurements for particle size and charge. Complementary techniques will include synchrotron-based SAXS/WAXS, scanning and transmission electron microscopy. The PhD project is part of the ERC Consolidator project CRYSTAL CLEAR, and will be conducted in close collaboration with a recently started PhD project that investigates the impact of ionic ratio on barite and calcite formation using similar experimental and analytical techniques. In the near-future, two postdoctoral researchers will join the team to further develop the theoretical framework for both projects.

As part of the personal PhD-training programme, the candidate is expected to assist in the teaching programmes of the Department of Earth Sciences for a limited amount of time (around 10%).

We seek an enthusiastic PhD candidate holding an MSc degree (at the start of the contract) that ensures appropriate background knowledge in Environmental Sciences, Earth Sciences, Environmental Mineralogy, (Environmental) Chemistry, or Material Sciences. Experience in performing laboratory experiments, solid phase characterisation and/or chemical analysis methods is required.

You approach scientific problems with determination and are eager to develop multidisciplinary skills. You must be willing to travel abroad for synchrotron beamtimes and to present your research to an international research community. As this project requires close collaboration within the research team, candidates are expected to be excellent team players. You also have excellent written and spoken English skills and good general communicational skills.

We offer a position (1.0 FTE), initially for one year with an extension to a total of four years upon a successful assesment in the first year, and with the specific intent that it results in a doctorate within this period. The gross monthly salary ranges between €2,325 in the first year and €2,972 (scale P according to the Collective Labour Agreement Dutch Universities) in the fourth year for a full-time employment. Salaries are supplemented with a holiday bonus of 8% and a year-end bonus of 8.3% per year. In addition, Utrecht University offers excellent secondary conditions, including an attractive retirement scheme, (partly paid) parental leave and flexible employment conditions (multiple choice model). More information about working at Utrecht University can be found here.

Facilities for sports and child care are available on our main campus (where the Department of Earth Sciences is situated), which is located only 15 minutes away from the historical city centre of Utrecht. You will also profit from the training activities through the Graduate School of Geosciences and Analysis-Technique-specific summerschools.

A better future for everyone. This ambition motivates our scientists in executing their leading research and inspiring teaching. At Utrecht University, the various disciplines collaborate intensively towards major societal themes. Our focus is on Dynamics of Youth, Institutions for Open Societies, Life Sciences and Sustainability.

Utrecht University's Faculty of Geosciences studies the Earth: from the Earth's core to its surface, including man's spatial and material utilisation of the Earth - always with a focus on sustainability and innovation. With 3,400 students (BSc and MSc) and 720 staff, the Faculty is a strong and challenging organisation. The Faculty of Geosciences is organised in four Departments: Earth Sciences, Human Geography & Spatial Planning, Physical Geography, and Sustainable Development.

The Department of Earth Sciences conducts teaching and research across the full range of the solid Earth and environmental Earth sciences, with activities in almost all areas of Geology, Geochemistry, Geophysics, Biogeology and Hydrogeology. The department hosts a highly international group of more than 100 PhD students and postdoctoral researchers and houses a wide variety of world-class laboratories. You will be working within the Geochemistry group which focuses on the geochemistry of the Earth’s surface. The group combines field data with experimental, modeling and theoretical approaches to elucidate biogeochemical cycles and mineral transformations along the aquatic continuum, e.g. from weathering of rocks to biogeochemistry of deep-sea sediments. We investigate (bio)geochemical processes from the nanometer to the global scale and utilize the geological record to better project Earth surface conditions in the future.