Nanometry on selected single crystals

The central term of the applied project is "nanometry", a combination of several experimental and theoretical methods in order to resolve physical properties on a nanometer- or sub-nanometer scale. As experimental tools we intend to use the single crystal Mössbauer spectroscopy (SCMBS) and X-ray diffractometry. The former shall serve to determine the experimental electric field gradient (efg) - a central quantity in the relationship of structure and physical properties. The latter shall help to evaluate electron densities in order to derive a semi-quantitative/-theoretical efg in the crystal unit cell by an already developed 3D plotting and calculating routine, which my be regarded as a super-microscope or "nanoscope" because the resolution is on the atomic scale. A modern full-quantitative/-theoretical method in the frame of the famous density functional theory should provide the mathematical background of the derived efg-orientations and -values. As supplementary methods for additional informations we plan to perform neutron diffraction eperiments (for magnetic moment alignments) or optical measurements by spectral photometry. All the methods will be applied to mineral single crystal samples with different scientific potential: 1) a famous synthetic and natural gem mineral (alexandrite) with extensive pleochroism, where the site distribution of iron and mechanism of optical properties will be evaluated 2) a synthetic solid solution between an Fe(II) mineral (fayalite) and the Fe(III) containing compound (the rather new mineral laihunite) will be examined dependent on FeII/FeIII ratio and a broad temperature range from 4.2K (antiferromagnetic region) up to 300C. The site distribution of the FeIII-ions and the difficult magnetism and its mechanism will be the scientific challenge here. The combination of the methods mentioned above is expected to give a much deeper insight into the relations of structure and physical properties (especially the efg) than the different tools of their own. In a preceding project we already evaluated the basic principles of this rather new proceeding and gained a valuable detailed explanation of the physical properties of fayalite Fe2SiO4.

The central term of the applied project is "nanometry", a combination of several experimental and theoretical methods in order to resolve physical properties on a nanometer- or sub-nanometer scale. As experimental tools we intend to use the single crystal Mössbauer spectroscopy (SCMBS) and X-ray diffractometry. The former shall serve to determine the experimental electric field gradient (efg) - a central quantity in the relationship of structure and physical properties. The latter shall help to evaluate electron densities in order to derive a semi-quantitative/- theoretical efg in the crystal unit cell by an already developed 3D plotting and calculating routine, which my be regarded as a super-microscope or "nanoscope" because the resolution is on the atomic scale. A modern full-quantitative/-theoretical method in the frame of the famous density functional theory should provide the mathematical background of the derived efg-orientations and -values. As supplementary methods for additional informations we plan to perform neutron diffraction eperiments (for magnetic moment alignments) or optical measurements by spectral photometry. All the methods will be applied to mineral single crystal samples with different scientific potential: 1) a famous synthetic and natural gem mineral (alexandrite) with extensive pleochroism, where the site distribution of iron and mechanism of optical properties will be evaluated 2) a synthetic solid solution between an Fe(II) mineral (fayalite) and the Fe(III) containing compound (the rather new mineral laihunite) will be examined dependent on FeII/FeIII ratio and a broad temperature range from 4.2K (antiferromagnetic region) up to 300C. The site distribution of the FeIII-ions and the difficult magnetism and its mechanism will be the scientific challenge here. The combination of the methods mentioned above is expected to give a much deeper insight into the relations of structure and physical properties (especially the efg) than the different tools of their own. In a preceding project we already evaluated the basic principles of this rather new proceeding and gained a valuable detailed explanation of the physical properties of fayalite Fe2SiO4.