Structure and Dielectric Properties of the Ba(Mg1/3Nb2/3)O3-La(Mg2/3Nb1/3)O3 System |
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| Authors: | Mehmet A Akbas Peter K Davies |
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| Affiliation: | Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104–6272 |
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| Abstract: | A complete range of perovskite solid solutions can be formed in the (1 ? x )Ba(Mg1/3Nb2/3)O3- x La(Mg2/3Nb1/3)O3 (BMN-LMN) pseudobinary system. While pure BMN adopts a 1:2 cation ordered structure, 1:1 ordered phases are stabilized for 0.05 ≤ x ≤ 1.0. Dark-field TEM images indicate that the La-doped solid solutions are comprised of large 1:1 ordered domains and no evidence was found for a phase-separated structure. This observation coupled with the systematic variations in the intensities of the supercell reflections supports a charge-balanced "random-site" model for the 1:1 ordering. The substitution of La also induces a transformation from a negative to positive temperature coefficient of capacitance in the region 0.25 ≤ x ≤ 0.5. |
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