Department of Chemistry and Biochemistry

Faculty

Cora Lind-Kovacs, PhDCLK
Professor
Email: cora.lind@utoledo.edu
Office: WO 2262
Phone: (419) 530-1505
Fax: (419) 530-4033

Professional Background:
Prediploma, 1996, Bergische Universität Wuppertal, Germany
M.S. 1999, Ph.D., 2001, Georgia Institute of Technology
Postdoctoral Associate, 2001-2003, Cornell University

Publications

Research Synopsis:
Synthesis and characterization of new and improved solids; non-hydrolytic sol-gel chemistry; negative thermal expansion materials; polymer composites; powder x-ray methods; Rietveld method. 

The Lind-Kovacs group will be pursuing research in the following target areas: 1) Synthesis and characterization of new negative thermal expansion (NTE) materials in the Sc2W3O12 family, 2) Incorporation of NTE materials into polymers, and 3) Development of in situ methods for the preparation of inorganic/polymer composites.

Negative thermal expansion (NTE) materials

While most solids expand upon heating, a few classes of materials shrink with increasing temperature. This unusual property is based on the compounds' crystal structures. It has attracted growing attention during the last decade, as it can be used to counterbalance the normal, positive thermal expansion of other materials through the preparation of composites.

There are many factors that influence the usefulness of NTE materials for composites (temperature range over which NTE is observed, occurrence of temperature or pressure induced phase transitions, ease of preparation etc.). For each specific application, additional factors like magnitude of the expansion coefficient, compatibility with other composite components, and stability under the expected processing conditions, need to be considered. To date, no "ideal" NTE material has been prepared, limiting the choice of composite components to the "most suitable" NTE material instead.

Research in our group will focus on the preparation of new materials in the Sc2W3O12 family. This family shows the strongest dependence of expansion behavior on cation identity. The use of non-hydrolytic sol-gel chemistry allows the incorporation of a larger variety of cations than those accessible by traditional ceramic methods, and facilitates the preparation of highly homogenous mixed cation compounds. The expansion behavior of the resulting materials will be characterized by variable temperature powder x-ray diffraction in combination with Rietveld analysis.

Polymer/NTE composites

Weare collaborating with the Coleman group in chemical engineering to prepare polymer composites containing the NTE material cubic ZrMo2O8. For the preparation of composites, control of particle size and shape are important. In addition, the surface of the oxide particles has to be modified with groups that allow a favorable interaction with the polymer matrix.

Development of in situ methods for the preparation of inorganic/polymer composites

The preparation of inorganic/polymer composites often involves multiple synthesis steps that lead to preformed inorganic particles and/or preformed polymer, followed by modifications to achieve compatibility between the two components, before the final mixing step that results in composites. We have recently started to explore the feasibility of developing true one-pot in situ methods for the preparation of inorganic/polymer composites, in which the inorganic phase and the polymer form simultaneously under mutually compatible conditions.

Notes for Crystallography Course

Last Updated: 12/1/20