Dr. Igor Levin

Research Interests

• Determination of local structure in inorganic materials using combined input from x-ray/neutron diffraction, electron microscopy imaging, and spectroscopic techniques;

• Determination of crystal structures, phase transitions, and structure-property relations in bulk and thin film electronic ceramics;

• Characterization of nanoscale structural and compositional heterogeneities in inorganic materials using high-resolution transmission electron mcroscopy and electron energy loss spectroscopy
  

Figure 1(left): Simultaneous RMC fits of mutiple types of data for perovskite-type Sr(Al_½Nb_½)O₃ .; Figure 2(center): Diffuse scattering in electron diffraction from a complex perovskite due to short-range cation ordering.; Figure 3(right): HRTEM image of a perovskite with  A-site cation vacancies. Atomic columns containing vacancies appear as dark crosses. Short-range order is observed.

Postdoctoral Research opportunities

Emerging electronic oxides (e.g. dielectrics, ferroelectrics, ionic conductors) frequently exhibit local atomic arrangements that are significantly different from those described by the average atomic positions as inferred from traditional crystallographic methods. The research includes experimental measurements on industrially-pertinent materials using a range of advanced techniques (transmission electron microscopy, x-ray and neutron diffraction, x-ray absorption fine structure, and Raman spectroscopy) and development of data analysis approaches and computer software for simultaneous structural refinements using multiple types of data

Accurate knowledge of atomic arrangements and internal substructure in nanomaterials is a key to understanding their properties. The project seeks to address this measurement problem by integrating theoretical analyses and several critical experimental techniques including total x ray and neutron scattering for extracting atomic pair distribution functions, small-angle scattering, and extended absorption fine structure measurements. NIST’s Ceramics Division has access to state-of-the-art synchrotron and neutron radiation facilities for these measurements.

Awards and Honors

• The Spriggs Phase Equilibria Award, American Ceramic Society, 2006
• Visiting Professor, University of Sheffield, Sheffield, UK, 2004
  
• Minerva Fellowship, Max-Planck Institut, 1995