The microstructure of ordered Ba(Mg_1/3Ta_2/3)O₃

Abstract

AESTRACTThe microstructure of the ordered perovskite Ba(MgIl3Ta2j3)O3 was studied by means of direct imaging, using high-resolution electron microscopy, and by means of selected-area electron diffraction. 'Single' crystals are shown to be fragmented at different structural levels. The cubic Ba03 framework contains numerous twins and stacking faults. Single domains of this framework are further fragmented by the potential occurrence of four orientation variants and of three translation variants in each orientation variant of the superstructure. The observations are consistent with the assumption that, at a temperature close to the melting point, an order-disorder transition of the B-cation sublattice occurs within the already-formed Ba03 framework. 2 f 2+ 5+

Atomic Resolution Transmission Electron Microscopy of the Microstructure of Ordered Ba(Cd1/3Ta2/3)O3 Perovskite Ceramics

“…The other <111> zones produce a lozenge‐shaped pattern consisting of basic nodes only. The selected‐area electron diffractions for Ba(Cd 1/3 Ta 2/3 )O 3 ceramics in the present work confirm the reciprocal space of the ordered structure of Ba(B′ 1/3 Ta 2/3 )O 3 perovskite ceramics described by Lei et al 19 …”

“…Recently, the reciprocal space of the ordered structure of Ba(Mg 1/3 Ta 2/3 )O 3 was analyzed in detail, 19 which has a crystalline structure similar to ordered Ba(Cd 1/3 Ta 2/3 )O 3 ceramics. There are two types of <110> zone patterns for the ordered structure.…”

Determination of 1:2 Ordered Domain Boundaries in Ba[(Co, Zn, Mg)1/3Nb2/3]O3 Dielectric Ceramics

“…The 1/3[111] c superlattice reflections visible from the fundamental reflections originate from the B‐site chemical ordering and correspond to the tripling of the cell along [111] c direction. According to literatures ever reported, a rectangle which represents 4 × 4 hexagonal unit cell is marked.…”

“…The hexagonal unit cell is marked by red rectangle, the twin relationship is easy to observe. This coherent twin boundary can be expressed as a stacking structure “…A‐B‐C‐A‐B‐C‐B‐A‐C‐B‐A…” . Analogously, A‐type boundary, which parallels to (001) c plane, can also be schematized [see Fig.…”

“…Twin boundaries separate different orientational variants, while APBs separate the translational variants . Single APB is considered to be nonconservative, which appears to have a disordered region with a width of several atomic distances .…”