HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF (BASRCA)TIO3 CERAMICS

(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.