Maimon C. Rose, R. E. Cohen
We use molecular dynamics with a first-principles-based shell model potential to study the electrocaloric effect (ECE) in lithium niobate, LiNbO3, and find a giant electrocaloric effect around Tc. The ECE is large even above the transition temperature and critical point along the Widom line. Below Tc we find that polarization switching falls along a line with Tc and the Widom line, showing that a connection exists between thermodynamics and kinetics in polarization switching. We investigate the effects of pressure, temperature and applied electric field on the ECE. The behavior we observe in LiNbO3 should generally apply to ferroelectrics, so that the operating temperature should be above Tc to obtain large electrocaloric response for refrigeration and energy scavenging applications. The relationship among Tc, the Widom line and homogeneous switching suggests universal behavior among ferroelectrics, relaxors, multiferroics and ferromagnets.
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http://arxiv.org/abs/1207.1685
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