Synthesis and Characterization of Intergrowth Bismuth Layered Structure Ferroelectrics in the System SrO-Bi2O3-TiO2

Abstract

Intergrowth bismuth layered structure ferroelectrics (BLSFs) in the system SrO-Bi2O3-TiO2 have been investigated with an objective to improve the dielectric and ferroelectric properties of them. There are three BLSFs in this system namely Bi4Ti3O12 (BIT), SrBi4Ti4O15 (SBTi4) and Sr2Bi4Ti5O18 (SBTi5) and one stable intergrowth BLSF compound between BIT-SBTi4. All these BLSFs compounds have been synthesized through a modified oxalate route. Their phase formation behavior during synthesis has been investigated in details using TG/DSC and XRD analysis. The crystal structures of all the compounds were refined through Rietveld
analysis to find accurate lattice parameters. Densification characteristics, microstructure
development, dielectric and ferroelectric properties of all compounds were analysed and
correlated with each other. The major findings were:
i. BIT-SBTi4 intergrowth compound showed an enhanced 2Pr than their individual constituent BIT and SBTi4. ii. Only a short range intergrowth structure between SBTi4-SBTi5 could be possible, which showed a broaden permittivity temperature characteristics.
iii. The remnant polarization of BIT-SBTi4intergrowth has been enhanced with Nb doping and doping helps in reducing oxygen vacancy in the ceramics.
iv. The ferroelectric properties of Nb modified BIT-SBTi4 intergrowth can be further enhanced by the La substitution for Bi in the structure, however with a disadvantage of decreased Tc.
v. Keeping the Tc unchanged, the ferroelectric property of the intergrowth can be improved by CuO addition, which helps in better densification of the ceramics.