Anomalous Pyroelectric Effect

Anomalous pyroelectric effect has been repeatedly observed in ferroelectric films which were compositionally graded or in which strain gradient or temperature gradient was realized. The effect is represented by the shift of the hysteresis P(E) loop center due to the change of temperature. Here we propose a new interpretation of this property. It is based on the assumption that the concentration gradient induces additional polarization. This is characterized by macroscopic description based on the modified Landau-Devonshire thermodynamic potential f(P). The graphical representation of this modified potential is an asymmetric double-well. The hysteresis phenomenon is described by the motion of the “representative Brown particle” in this double-well; the shape of the latter is modulated by the time-dependent electric field. The observed anomalous pyroelectric effect is based on the coherence of the asymmetry and kinetic aspect of the phenomenon.

Keywords:

• Anomalous pyroelectricity
• compositionally graded film
• hysteresis loop

Classification codes:

• 77.55.+f
• 77.70.+a
• 77.80.Fm

Acknowledgment

The work of the first author was sponsored by Czech Grant Agency under Grant No. 202/03/0551. The work of the second author was sponsored by Ministry of Education of Czech Republic under Research Program MSM 242200002.