Effect of M{sup 4+} (Ce, Sn, Ti) B-site substitutions on the cation ordering in Ba(Mg{sub 1/3}Ta{sub 2/3})O{sub 3}
- Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Materials Science and Engineering
The effect of different tetravalent octahedral site substitutions on the cation ordering in Ba(Mg{sub 1/3}Ta{sub 2/3})O{sub 3} perovskites were explored by investigating the phase stabilities and structures of their solid solutions with BaTiO{sub 3}, BaSnO{sub 3}, and BaCeO{sub 3}. In the cerate system, the 1:2 ordered form of Ba(Mg{sub 1/3}Ta{sub 2/3})O{sub 3} has very limited stability and transforms to a cubic, 1:1 ordered structure with a doubled perovskite repeat between 7 and 25 mol% BaCeO{sub 3}. Structure refinements of the Ba({beta}{prime}{sub 1/2}{beta}{double_prime}{sub 1/2})O{sub 3} phases indicate that the 1:1 order can be described by a random site model. In this model, the {beta}{double_prime} sites are occupied by Ta, the {beta}{prime} sites are occupied by a random distribution of Mg, Ce, and the remaining Ta cations, and the stoichiometry of the structure can be represented by Ba[Mg{sub 2(1{minus}x)/3}Ta{sub (1{minus}4x)/3}Ce{sub 2x}]{sub 1/2}[Ta]{sub 1/2}O{sub 3}. Although the formation of this phase in the cerate system is similar to the results reported previously for BaZrO{sub 3} substitutions, no evidence of 1:1 order was found in the BaTiO{sub 3} solid solutions, which adopt a disordered perovskite structure for >10 mol% Ti. The correlation between the size of the tetravalent cation and the formation of the random site structure extended to the BaSnO{sub 3} system, which also showed no evidence of an extended region of stable 1:1 order.
- OSTI ID:
- 638345
- Journal Information:
- Materials Research Bulletin, Vol. 33, Issue 8; Other Information: PBD: Aug 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Formation and structural characterization of 1:1 ordered perovskites in the Ba(Zn{sub 1/3}Ta{sub 2/3})O{sub 3}-BaZrO{sub 3} system
Order-disorder in In{sup 3+} perovskites: The example of A(In{sub 2/3}B''{sub 1/3})O{sub 3} (A=Ba, Sr; B''=W, U)