K. Koseki et al., HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF (BASRCA)TIO3 CERAMICS, Physica status solidi. a, Applied research, 143(2), 1994, pp. 245-253
(BaSrCa)TiO3 ceramics used as varistors are investigated by high-resol
ution electron microscopy with the aid of image simulation. Two sample
s prepared by slightly different reducing heat treatments are observed
. One is composed of large crystalline grains and microcrystalline reg
ions (or grains), both of which have the same chemical composition, an
d also amorphous grain boundary areas rich in SiO2, MgO, and BaO. The
other is only composed of well-developed crystalline grains with a bou
ndary of facet structure. The interface between facets of the bicrysta
ls is the composition plane of the (111bar) twin, and is not a Ti laye
r but a (BaSrCa)-O3 layer. The atomic projection of the crystals near
the grain boundary is also described.