  In order to understand the physical hysteresis loops clearly, we constructed
a novel model, which is combined with the electric field, the temperature, and
the stress as one synthetically parameter. This model revealed the shape of
hysteresis loop was determined by few variables in ferroelectric materials: the
saturation of polarization, the coercive field, the electric susceptibility and
the equivalent field. Comparison with experimental results revealed the model
can retrace polarization versus electric field and temperature. As a
applications of this model, the calculate formula of energy storage efficiency,
the electrocaloric effect, and the P(E,T) function have also been included in
this article.
