Evolution of the chemical bonding nature of ferroelectric bismuth titanate upon cation substitution

Abstract

The effect of cation substitution on the crystal and electronic structures of ferroelectric bismuth titanate has been systematically investigated. According to the x-ray diffraction analyses on Bi3.25A0.75Ti3O12 (A=Bi, La, Gd, and Y), it was found that the cation substitution gives rise to the contraction of the volume of the unit cell and to the decrease of the structural distortion of the bismuth titanate, as well. The present x-ray absorption spectroscopic results reveal that the local structural change upon chemical reduction is remarkably depressed by the cation substitution through the enhancement of (TiO) bonds. Such a stabilization of TiO6 octahedra can be understood by a competition between adjacent (BiO) and (TiO) bonds as well as the contraction of the unit cell.

Unique Properties of 2 D Layered Titanate Nanosheets as a Building Block for the Optimization of the Photocatalytic Activity and Photostability of TiO2‐Based Nanohybrids

“…In the pre-edge region, there are several preedge peaks P 1 , P 2 , and P 3 corresponding to the transitions from core 1s level to unoccupied 3d states. [28] The pre-edge peaks of the 0D-TOAP nanohybrids show fairly similar spectral feature to those of the anatase-type TiO 2 material, confirming the higher content of the anatase TiO 2 phase in this material. Conversely, there is a strong similarity in the pre-edge spectral features of the 2D-TOAP nanohybrids and the reference layered titanium oxide, highlighting the maintenance of the original layered structure of titanium oxide component in the 2D-TOAP material.…”

“…The peak A is assigned as a transition with the shakedown process whereas the peaks B and C at higher energy are attributed to transitions from core 1s orbital to out-of-plane 4p z one and to in-plane 4p x,y one, respectively. [28] The relative intensity of the peaks B and C reflects sensitively the local atomic arrangement around titanium ions. [29,30] The rutile TiO 2 reference displays the well-resolved peaks B and C, in which the intensity of the peak C is much stronger than that of the peak B. Conversely, a sharp feature B with very weak peak C is discernible for the anatase TiO 2 .…”

Cocatalyst‐Free Photocatalysts for Efficient Visible‐Light‐Induced H2 Production: Porous Assemblies of CdS Quantum Dots and Layered Titanate Nanosheets

“…Such a spectral similarity between the nanohybrids and lepidocrocite-structured layered titanates was also observable for the main-edge peaks denoted as A, B, and C, which could be assigned as dipoleallowed 1s → 4p transitions. [ 37 ] The overall spectral features of the nanohybrids are clearly distinguishable from those of anatase and rutile TiO 2 . These XANES results underscore the maintenance of the lepidocrocite-type layered structure of the titanate after the hybridization with the CdS QDs.…”

“…All of the present materials show three pre-edge peaks (denoted as P 1 , P 2 , and P 3 ), which are related to the transitions from the core 1 s level to the unoccupied 3 d states. [ 36,37 ] The overall spectral features of these pre-edge peaks provide a sensitive measure for the local atomic arrangement around the titanium ions. [ 37 ] Both the CdTi nanohybrids display the …”

“…[ 36,37 ] The overall spectral features of these pre-edge peaks provide a sensitive measure for the local atomic arrangement around the titanium ions. [ 37 ] Both the CdTi nanohybrids display the …”