CORRELATION BETWEEN LOCAL STRUCTURES AND PARTIAL ELECTRONIC BAND STATES IN FERROELECTRIC Bi4-XLaXTi3O12

Abstract

The local structures and the partial band states near a Fermi level (E-F) have been studied at room temperature in the ferroelectric phase of Bi4-XLaXTi3O12 (BLT) with 0.00 <= x <= 1.46 by means of X-ray absorption spectra (AAS) including EXAFS and XANES. The EXAFS spectra suggest that, as increasing the substituted La ions, the local structures around Ti and Bi ions in perovskite-blocks of (Bi2-XLaXTi3O10)(-2) are gradually deformed the x = 0.85, and are largely changed by a structural phase transition occurring between x = 0.85 and 1.20. The XANES spectra suggest that there is a strong hybridization hetween Ti-3d(t(2g)) and O-2p bands and between Bi-6s and O-2p bands in the valence band states, while between Ti-3d(e(g)) and O-2p hands and Bi-6p and O-3s hands in the conduction band states. All of the XAS show interesting dependency on the concentration of the substituted La ions in BLT The results suggest that, in BLT a reducing spontaneous polarization induced by the La-substitution resultsftom the deformation ofthe local structures around Ti and Bi ions andftom modulation of the hybridized hand states near E-F.