Wayne State University

Researchers from Wayne State University, University of California Santa Barbara and University of Southampton, UK, discover that the solid material, Bi2Ti2O7, may be both glass and crystal; May lead to new types of electronic materials

Dr. Gavin LawesDETROIT—Most solid materials can be neatly divided into two structure systems – crystal or glass. Crystal structures have atoms that fall in to a well-ordered lattice structure, and glass structures have atoms that fall randomly. A team of researchers have discovered that one particular material, Bi2Ti2O7, exhibits unusual characteristics of both glass and crystal. 

According to the researchers, the positively charged nuclei of the material are ordered in a crystalline structure, while the positions of the negatively charged electrons are random. “This mixture of crystalline and glassy behavior has been observed previously in magnetic systems, but the identification of this behavior in Bi2Ti2O7 could confirm a new type of electronic order,” stated Gavin Lawes, Ph.D., assistant professor of physics at Wayne State University and resident of Grosse Pointe Woods, Mich.

Their conclusions, found in the June 2009 issue of Physical Review B by The American Physical Society, are based on evidence that low temperature measurements of the thermodynamic properties of Bi2Ti2O7  is an experimental realization of a “charge ice” system, where the electronic disorder arises because the electrostatic interactions are frustrated by the geometry of the underlying atomic lattice. 

“This result is significant,” commented Lawes, “because the properties of the disordered electrons in a crystalline material may be very different than what is observed in conventional crystalline systems.” This discovery may ultimately lead to new types of technologically important electronic materials.

For more information, contact Julie O'Connor at ag2712@wayne.edu or 313-577-8845.
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Wayne State University is one of the nation’s pre-eminent public research universities in an urban setting, ranking in the top 50 in R & D expenditures of all public universities by the National Science Foundation. Through its multidisciplinary approach to research and education, and its ongoing collaboration with government, industry and other institutions, the university seeks to enhance economic growth and improve the quality of life in the city of Detroit, state of Michigan and throughout the world. For more information about research at WSU, visit http://www.research.wayne.edu .