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Summary: Dielectric tunability of graded barium strontium titanate multilayers: Effect
of thermal strains
M. B. Okatan,1,2
M. W. Cole,3,a
and S. P. Alpay1,2,b
1
Materials Science and Engineering Program, Department of Chemical, Materials, and Biomolecular
Engineering, University of Connecticut, Connecticut 06269, USA
2
Institute of Material Science, University of Connecticut, Connecticut 06269, USA
3
U. S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground,
Maryland 21005, USA
Received 12 August 2008; accepted 14 October 2008; published online 19 November 2008
A thermodynamic model was developed to analyze the effect of the difference in the thermal
expansion coefficient TEC of a multilayered barium strontium titanate Ba1-ySryTiO3 BST
ferroelectric heterostructure and a passive substrate on the dielectric properties by taking into
account electrostatic and electromechanical interactions between the ferroelectric layers. Results
show that the dielectric constant and tunability can be maximized by minimizing the TEC mismatch.
Furthermore, lower processing temperatures lead to lower thermal strains and thus to better
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