Electron microscopy
 
Stability of Ferroelectrics Related to Oxygen Vacancies
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In ferroelectrics, a significant improvement of stability is achieved with the application of multi-layer interstitial ferroelectric compounds, e.g. (Bi2O2)2+(Am−1BmO3m+1)2−, here A = Ca2+, Sr2+, Ba2+, Pb2+, Bi2+, or La3+ and B = Ti4+, Ta5+, or Nb5+. For instance, for m = 2, Bi2O2 layers are alternated with perovskite-like AB2O7 layers with double oxygen octahedral units. [1, 2] In this system, because the oxygen ions in the perovskite-like layers are more stable than those in the stacked Bi2O2 layers [3], the Bi2O2 layers are an oxygen source which compensates for the oxygen vacancies in perovskite-like octahedra. Therefore, the oxygen vacancies that are normally generated in the perovskite-like layers to cause fatigue can easily be exchanged with oxygen ions in the Bi2O2 layers [4], resulting in much smaller fatigue.

 

 

 

[1] C.A. Paz de Araujo, J.D. Cuchiaro, L.D. McMillan, M. C. Scott, J. F. Scott: Nature 374, 627 (1995).
[2] T. Sumi, N. Moriwaki, G. Nakane, T. Nakakuma, Y. Judai, Y. Uemoto, Y. Nagano, S. Hayashi, M. Azuma, E. Fujii, S. Katsu, T. Otsuki, L. McMillan, C. A. Paz de Araujo, G. Kano: Tech. Dig. Int. Solid-State Circuits Conf., San Francisco (1994) p. 268.
[3] B.H. Park, S.J. Hyun, S.D. Bu, T.W. Noh, J. Lee, H.-D. Kim, T.H. Kim, W. Jo: Appl. Phys. Lett. 74, 1907 (1999).
[4] O. Auciello, A.R. Krauss, J. Im, D.M. Gruen, E.A. Irene, R.P.H. Chang, G. E. McGuire: Appl. Phys. Lett. 69, 2671 (1996).

 

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