The major electrical long-term failure mechanisms in ferroelectrics are:
        i) Polarization fatigue.
            In FRAM applications, the loss of remanent polarization is a key issue after a continuous electric field cycling of negative and positive biasing (cyclic read and write operations). [1,2]
        ii) Retention loss.
            In practice, a ferroelectric material cannot retain the polarization for a long time due to a reduced difference between the switching and non switching charges.
        iii) Imprint.
            This is the tendency of one polarization state to be more stable than the opposite one, which results in the loss of polarization. The imprint affects the ferroelectric nature by shifting the ferroelectric hysteresis loop, which makes it difficult to distinguish and address the write and read modes.

[1] H. Ishiwara, M. Okuyama, Y. Arimoto (Eds.): Ferroelectric Random Access Memories, Topics Appl. Phys. 93, 139–149, (2004).
[2] H. Kohlstedt, Y. Mustafa, A. Gerber, A. Petraru,M. Fitsilis, R. Meyer, U. Böttger and R Waser., Microelec. Engg, 80, 296–304, (2005).