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Influence of mechanical boundary conditions on the electrocaloric properties of ferroelectric thin films
 

Summary: Influence of mechanical boundary conditions on the electrocaloric
properties of ferroelectric thin films
G. Akcay, S. P. Alpay,a
and G. A. Rossetti, Jr.
Materials Science and Engineering Program, University of Connecticut, Storrs, Connecticut 06269, USA
and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA
J. F. Scott
Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom
Received 24 October 2007; accepted 10 November 2007; published online 25 January 2008
A thermodynamic analysis of the electrocaloric EC effect in BaTiO3 ferroelectric thin films has
been carried out under differing mechanical boundary conditions. It is shown that both the
magnitude of the electrocaloric effect and temperature at which it is maximized depend not only on
the extent of the applied field change but also on the value of the initial field. For initial fields
smaller than a critical value the EC effect is largest at the phase transition temperature but the effect
is a strong function of temperature. For external electrical fields larger than this value, conversely,
the EC effect is the largest at a higher temperature and is a weak function of temperature. Perfect
lateral clamping transforms the first-order phase transition into a second-order transition, lowering
the magnitude of the electrocaloric effect and dependence on temperature. Compressive and tensile
misfit strains also alter the nature of the phase transition and affect the electrocaloric properties in
an analogous way. A compressive misfit strain shifts the maximum in the EC effect to higher

  

Source: Alpay, S. Pamir - Department of Materials Science and Engineering, University of Connecticut

 

Collections: Materials Science