Projects / Programmes
Nanoscale investigations of diffusion controlled topotaxial phase transformations in rutile-corundum host systems
| Code |
Science |
Field |
Subfield |
| 1.06.00 |
Natural sciences and mathematics |
Geology |
|
| Code |
Science |
Field |
| P420 |
Natural sciences and mathematics |
Petrology, mineralogy, geochemistry |
| Code |
Science |
Field |
| 1.05 |
Natural Sciences |
Earth and related Environmental sciences |
oriented recrystallization, solid state diffusion, Fe-Ti oxides, petrology, applied mineralogy
Researchers (14)
Organisations (3)
Abstract
Oriented mineral intergrowths occur in all types of rocks and contain important implications about the past petrogenetic processes. They form among structurally related minerals as a result of topotaxial phase transformations (TPTs) or epitaxial growth on host mineral phase. During solid-state TPTs, the precursor crystal is transformed into one or more products along special crystallographic directions, leading to the formation of 3D oriented intergrowths. Atomic rearrangements are activated by a combination of geochemical and geophysical changes that trigger diffusion processes inside the host crystal to reach a new equilibrium condition. The processes start at the nanoscale, therefore nanosized phenomena like precipitates and phase boundaries contain key structural and chemical indications for reconstruction of mechanisms leading to the formation of oriented mineral intergrowths.
Intergrowths related to TPTs are especially common in the Fe-Ti oxide group of minerals, which is recently receiving much attention in the studies of oxygen fugacity conditions associated with phase transformations in ultramafic igneous and metamorphic rocks. Our previous analyses of complex topotaxial phase transformations (TPT) in ferrian–ilmenite and its transition to more oxidized products such as hematite and rutile have given us a wealth of information on these processes. Based on nanoscale studies of reaction interfaces we show that TPTs are extremely sensitive to temperature and oxygen fugacity. These can be determined from the orientation relationship (OR) between the product and reactant phases, i.e. rutile/ilmenite, that is finely tuned by the temperature of exsolution defining what is the most stable interface, and oxygen fugacity, that controls the kinetics of the whole process. The processes during TPTs of different precursor minerals are not fully understood, especially not at the atomic scale, and will be the main focus of investigations within this project.
For our studies we will use rutile/host exsolutions from different origins. We have access to an extensive collection of samples displaying diverse rutile exsolutions with known geological backgrounds that will serve as reference objects to corroborate our scientific approach. The first goal of our investigations will be in-depth understanding the geochemical and geophysical reasons for the formation of crystallographically different rutile intergrowths during TPT processes from different precursors. In addition to characterization of natural intergrowths, recrystallization of different precursor minerals under laboratory conditions will be studied. These findings will have important implications in understanding processes during the petrogenesis of different types of rocks. Nanoscale studies of the samples using advanced methods of electron microscopy will be targeted to provide information on the sequence of TPT processes down to the atomic scale. Third part of the studies will be dedicated to synthesis of functional materials according to the principles of TFTs.
The main objectives within proposed project will be: (1) Deciphering TPT processes in selected rutile/host systems at the atomic scale (2) Interpreting solid-state reactions and diffusion processes within the host mineral during TPTs leading to different rutile intergrowths by targeted TPT experiments as a function of T and fO2 at the laboratory scale and finally (3) Implementation of TPT mechanisms for the production of desired rutile/host intergrowths and testing for selected nanotechnology applications (energy, environmental). The project team is multidisciplinary and involves mineralogists, chemists, physicists and materials scientists with expertise in electron microscopy, thermodynamics and crystallography, each contributing a high impact publications in their research fields.
Significance for science
Investigations of twinning, epitaxies and phase transformations in minerals that our research group has been conducting for many years, represent one of the fundamental scientific challenges in study of rock-forming mechanisms. The results of proposed research will be an important contribution to the understanding of key processes in the construction of rocks. The foundations for nanostructural investigations of phase transformations in minerals and their relation to materials science were outlined during our previous two research projects, J1-4167 and J1-6742. Our approach in solving fundamental challenges in the field of mineralogy is innovative and, as such, represents a new research direction. We involve more and more researchers from Slovenia and abroad, with whom we systematically extend our knowledge to new systems, thus building solid foundations for this new field of research on a global scale. We solve difficult fundamental questions, not only in the area of petrology, but also from the fields of solid state chemistry and materials. The results of our research represent an important contribution to thermodynamics and kinetics of processes that take place during the growth of crystals and contribute to our in–depth understanding of basic building principles in crystalline solids at the atomic scale.
Topotaxial phase transformations, which will be central to this project, are of key importance for understanding diffusion processes and reactions in minerals, crucial for correct interpretation of the formation and transformation of magmatic and metamorphic rocks. The studied phenomena are a result of a complex sequence of events, each pointing to a specific change in the chemistry of fluids and the departure from the current equilibrium state. In our studies of selected model systems, we expect fundamental insights related to better understanding of processes involved in oriented recrystallization of rutile on various precursors at the atomic scale. The results will have important implications in mineralogy and petrology, and represent and innovative approach to synthesis of textured functional materials. Our achievements would not be possible without the use of novel microscopy methods. Within the proposed project, advanced methods of analytical microscopy at the atomic level will be used, while the knowledge that will be gained through the project will be applicable to development of modern materials.
All new knowledge, that will emerge from the proposed project, will be promoted through scientific publications, lectures at conferences and universities, and international exchange of researchers. The proof of the high quality of our work are numerous publications in scientific journals in field of mineralogy and materials science, invited lectures at international scientific conferences, and in the recent period, also invitations for participation in mineralogy related research projects from renowned foreign universities and research institutions.
Significance for the country
Investigations of twinning, epitaxies and phase transformations in minerals that our research group has been conducting for many years, represent one of the fundamental scientific challenges in study of rock-forming mechanisms. The results of proposed research will be an important contribution to the understanding of key processes in the construction of rocks. The foundations for nanostructural investigations of phase transformations in minerals and their relation to materials science were outlined during our previous two research projects, J1-4167 and J1-6742. Our approach in solving fundamental challenges in the field of mineralogy is innovative and, as such, represents a new research direction. We involve more and more researchers from Slovenia and abroad, with whom we systematically extend our knowledge to new systems, thus building solid foundations for this new field of research on a global scale. We solve difficult fundamental questions, not only in the area of petrology, but also from the fields of solid state chemistry and materials. The results of our research represent an important contribution to thermodynamics and kinetics of processes that take place during the growth of crystals and contribute to our in–depth understanding of basic building principles in crystalline solids at the atomic scale.
Topotaxial phase transformations, which will be central to this project, are of key importance for understanding diffusion processes and reactions in minerals, crucial for correct interpretation of the formation and transformation of magmatic and metamorphic rocks. The studied phenomena are a result of a complex sequence of events, each pointing to a specific change in the chemistry of fluids and the departure from the current equilibrium state. In our studies of selected model systems, we expect fundamental insights related to better understanding of processes involved in oriented recrystallization of rutile on various precursors at the atomic scale. The results will have important implications in mineralogy and petrology, and represent and innovative approach to synthesis of textured functional materials. Our achievements would not be possible without the use of novel microscopy methods. Within the proposed project, advanced methods of analytical microscopy at the atomic level will be used, while the knowledge that will be gained through the project will be applicable to development of modern materials.
All new knowledge, that will emerge from the proposed project, will be promoted through scientific publications, lectures at conferences and universities, and international exchange of researchers. The proof of the high quality of our work are numerous publications in scientific journals in field of mineralogy and materials science, invited lectures at international scientific conferences, and in the recent period, also invitations for participation in mineralogy related research projects from renowned foreign universities and research institutions.
Most important scientific results
Interim report
Most important socioeconomically and culturally relevant results
Interim report
