Cation Ordering Transformations
نویسندگان
چکیده
Single-phase perovskites were formed in the (1−x)Ba(Zn1/3Nb2/3)O3–(x)La(Zn2/3Nb1/3)O3 system for compositions with 0.0 ≤ x ≤ 0.6. Although the stability of the trigonal ‘‘1:2’’ ordered structure of the Ba(Zn1/3Nb2/3)O3 end member is very limited (0.0 ≤ x < 0.05), low levels of lanthanum induce a transformation to a cubic, ‘‘1:1’’ ordered structure that has a broad range of homogeneity (0.05 ≤ x ≤ 0.6). Samples with x > 0.6 were comprised of La3NbO7, ZnO, and a perovskite with x = 0.6. The cubic 1:1 phases were fully ordered and no evidence was found for a compositionally segregated microstructure. These observations could not be reconciled in terms of a ‘‘space-charge’’ model; rather, they supported a charge-balanced, ‘‘random-site’’ structure for the 1:1 cation-ordered Ba(b*1/2b(1/2)O3 phases.
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تاریخ انتشار 1998