抄録
In this work, we synthesized Bi4Ti3O12 and Bi4Ti2.85Si0.15O12 by means of a conventional solid-state reaction, and investigated their ferroelectric properties. From P-E hysteresis measurement, it was demonstrated that the Bi4Ti3O12 began to show higher remanent polarization and lower coercive field by partially substituting Si for Ti. In order to clarify how the substitution affected the crystal and electronic structures and thus ferroelectric properties, we performed X-ray absorption fine structure spectroscopy, synchrotron X-ray diffraction and neutron diffraction measurements. As a result, it was found by Rietveld analysis using neutron diffractions that local distortions of TiO6 octahedra increased by the partial substitution of Si for Ti. Taking it into account that such a distortion induces a polarization in a crystal, this may be one of the reasons why the substitution improved ferroelectric properties of Bi4Ti3O12. From electronic density distributions estimated by maximum entropy method, it was also suggested that Ti-O bond became stronger by the substitution.
