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Z-Contrast Imaging of Ordered Structures in Pb(Mg1/3Nb2/3)O3 and Ba(Mg1/3Nb2/3)O3

Published online by Cambridge University Press:  02 July 2020

Y. Yan ,
Z. Xu ,
D. Viehland  and
S. J. Pennycook
Y. Yan
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831-6030
Z. Xu
Affiliation:
Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois, 61801
D. Viehland
Affiliation:
Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois, 61801
S. J. Pennycook
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831-6030
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Extract

Lead-based cubic perovskites such as Pb(B2+1/3B5+2/3)O3 (B2+ = Mg, Co, Ni, Zn; B5+ = Nb, Ta) are relaxor ferroelectrics. Localized order and disorder often occur in materials of this type. In the Pb(Mg1/3Nb2/3)O3 (PMN) family, previous studies have proposed two models, space-charge and charge-balance models. In the first model, the ordered regions carry a net negative charge [Pb(Mg1/2Nb,/2)03], while in the second model it does not carry a net charge [Pb((Mg2/3Nb1/3)1/2Nb1/2)03]. However, no direct evidence for these two models has appeared in the literature yet. In this paper we report the first direct observations of local ordering in undoped and La-doped Pb(Mg1/3Nb2/3)03, using high-resolution Z-contrast imaging.

Because the ordered structure in Ba(Mg1/3Nb2/3)03 is well known, the Z-contrast image from an ordered domain is used as a reference for this study. Fig. 1(a) shows the projection of the supercell of fully ordered Ba(Mg1/3Nb2/3)03 along the [110] direction.

Type
Microscopy of Ceramics and Minerals
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 554 - 555
Copyright
Copyright © Microscopy Society of America

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References

References:

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5. This research was sponsored by the Division of Materials Sciences, U.S. Department of Energy, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation, and by appointment to the ORNL Postdoctoral Research Program administered jointly by ORISE and ORNL.Google Scholar