Microstructural studies on (1-x)Ba(Mg1/3Nb2/3)O3-xCa(Mg1/3Nb2/3)O3 (BCMN) complex perovskite compounds, which are mixtures of Ba(Mg1/3Nb2/3)O3 (BMN) and Ca(Mg1/3-Nb2/3)O3 (CMN), were conducted using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. Pure BMN and CMN both have a 1:2 ordered structure, via the chemical ordering of B-site cations; however, the tilting of oxygen octahedra is involved in pure CMN, whose structure has a 1:2 ordered monoclinic unit cell that is characterized by (±1/6,±1/6,±1/6)-type superlattice reflections in electron diffraction patterns along the  zone axis that is based on a simple cubic perovskite. Studies of the morphologic differences have indicated two types of inhomogeneities in a mixture of the BCMN system: (i) a rather large-scale segregation (i.e., grain sizes of several micrometers), where the grains are separated compositionally as being barium-rich or calcium-rich, and (ii) fine-scale lamellar-type segregations 20 nm wide and 200 nm long. The segregation that is caused by Ba and Ca ions can be identified by the difference of superlattice modulations from high-resolution transmission electron microscopy lattice images.
|Number of pages||6|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - 2000 Jan 1|
ASJC Scopus subject areas
- Ceramics and Composites
- Materials Chemistry