Universität Freiburg,
Institut für Mineralogie, Petrologie und Geochemie

Kontakt:

Ansprechpartner:	Prof. Dr. Reto Gieré
Fon:	+49-(0)761-203-6409
Fax:	+49-(0)761-203-6407
Anschrift:	Albertststraße 23b 79104 Freiburg
Internet:	http://www.minpet.uni-freiburg.de
E-Mail:	giere@.uni-freiburg.de

Main focus

Our research is interdisciplinary and involves scientists from several different countries and institutions. Collaborators have scientific backgrounds in areas such as crystallography, mineralogy, atmospheric chemistry, water chemistry, physics, biology, radiochemistry, chemical engineering, materials science, geochemistry or geology. By having widely different perspectives, each of our colleagues provides important scientific insights, thus creating a group in which we all learn from each other. Our group is currently concentrating its research efforts on three general topics:

1) Atmospheric pollutants:

our research is focused on the chemical and structural characterization of particulate emissions from coal-fired power plants. We also study the distribution of chemical elements between different types of particles. This research involves various analytical techniques, especially transmission electron microscopy for the nanoparticles. A large portion of the emitted particles is in the respirable range (i.e., < 2.5 micrometers in diameter). These particles, thus, pose a danger to human health because, when inhaled, they will remain in the lung tissue. One of our projects, therefore, is dedicated to the interaction between fly ash particles and lung fluids.

Transmission electron microscope images of glass spheres in fly ash. The crystals attached to the surface of the glass sphere on the left are Ca oxide and sulfate crystals.

2) Disposal of high-level nuclear waste:

our research concentrates on the characterization of minerals which serve as natural analogues for materials envisaged for the immobilization of high-level nuclear waste and plutonium. One of the strategies of immobilization of such nuclear waste is the use of titanate ceramics, which are specifically designed to accommodate a wide range of nuclides. Important phases in such ceramics include zirconolite, brannerite, and members of the pyrochlore group. Our natural analogue studies demonstrate that several titanium minerals contain radioactive elements in very high concentrations (up to 30 weight%) and retained them for millions of years. These minerals are extremely durable in the natural environment, even when surrounded by corrosive hot fluids or when exposed to tropical weathering. This unique property can be used to our advantage in the area of nuclear waste disposal. Together with the Australian and the US governments, we are also testing actual waste forms consisting of these phases.

Crystal structure of zirconolite, one of the titanium minerals that can be used for the diposal of high-level nuclear waste. The radionuclides occupy the Calcium (Ca) and Zirconium (Zr) sites of the structure, where they are encaged for millions of years.

3) Environmental mineralogy:

this area of research combines mineralogy and environmental science. All our research efforts are directed at applying mineralogy to serious environmental problems caused by human activity. We examine a wide range of topics and sites, and all research projects have the ultimate goal of understanding how toxic elements, mainly heavy metals, are best immobilized in minerals and their synthetic analogues. Our interests are primarily in the area of heavy metal binding to cement-based materials, and control of element mobility by primary or secondary minerals in waste sites and soils

Zinc distribution map showing some large CSH-particles with distinct Zn-rich rims. Largest particles are about 50 micrometers across.