High-pressure synthesis and properties of novel simple oxides with unusual stoichiometries

• Applicant: Dr. Sergey V. Ovsyannikov
• Subject Area: Experimental Condensed Matter Physics ; Synthesis and Properties of Functional Materials
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 402706186

Recent discoveries and studies of novel simple oxides of iron (FexOy) with hitherto unknown stoichiometries (e.g., Fe4O5, Fe5O6, Fe7O9, etc.), which can be synthesized at high-pressure high-temperature (HP-HT) conditions, showed that these oxides are of an exceptional interest for natural sciences. Alike magnetite (Fe3O4), these mixed-valent simple iron oxides present the perfect model systems to investigate the interrelations between the charge interactions and physical properties. In particular, the charge-ordering transitions of metal-insulator-type discovered in Fe3O4, Fe4O5 and Fe5O6 were found to be concurrent with extraordinary distortions in their crystal structures. The present project is dedicated to HP-HT synthesis and investigation of physical properties of novel simple oxides of three common transition metals, such as iron, titanium and manganese. We will synthesize novel mixed-valence phases of these simple oxides and investigate their electronic, optical, vibrational, mechanical, magnetic, and other properties in the wide ranges of temperatures and applied pressures. Our research will involve a variety of experimental techniques including but not limited to: single crystal X-ray diffraction, neutron diffraction, Mössbauer spectroscopy, Raman spectroscopy, Infrared and optical absorption spectroscopy, and measurements of different physical characteristics, such as: electrical resistivity, thermoelectric power, magnetic susceptibility, magnetization, dielectric constant, electric polarization, and others. This study seems to be highly important from both fundamental and applied perspectives. Results of these investigations would facilitate an understanding of physical properties of more complex strongly correlated oxides.

• DFG Programme: Research Grants