BYONG-SEO PARK 2 ) , JEONG-DAE KoH~), and WHA-TEK KIM SbSI : V, SbSeI : V, BiSI : V, and BiSeI : V single crystals are grown by the vertical Bridgman technique using ingots synthesized from mixtures of the elements (purity 99.9999%). The grown single crystals have an orthorhombic structure and an indirect energy band structure. The temperature dependence of the optical energy gap is well fitted by the Varshni equation. Impurity optical absorption peaks due to the doped vanadium appear and are assigned to the electron transitions between the energy levels of the Vz+ ion located at T, sites of the host lattice.

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A significant difference in dielectric nonlinearity was contrasted between fine- and coarse-grained BaTiO3-based multilayer ceramic capacitors. Grain growth resulted in a decrease in dielectric constant in low field but a steep increase with increase in alternating current field, which can be associated with a decrease in reversible and a significant increase in irreversible domain wall contribution from Preisach analysis. Fine-grained specimens showed almost cubic structure despite ferroelectric domain contrasts, which is anticipated to significantly reduce strain incompatibility during domain wall motion, and clean domain boundaries with no lattice defects. However, coarse-grained specimens with high aspect ratio of the tetragonal lattice should accompany lattice distortion with increased intergranular constraints during domain wall motion, and many lattice defects were observed near domain boundaries. These results demonstrate experimentally the presence of weak pinning centers in coarse-grained specimens, which inhibit domain wall motion in low alternating current fields. Long-range motion occurs beyond the threshold field and results in an abrupt increase in dielectric constant.

The influence of tetragonality (c/a) of the dielectrics of BaTiO3-based multi-layer ceramic capacitors (MLCC) on the direct current (dc) bias characteristics was investigated.