Micro‐Raman study of Zr‐substituted Bi 4 Ti 3 O 12 ceramics

We have studied the lattice vibrational modes of Zr‐substituted Bi 4 Ti 3 O 12 ceramics using micro‐Raman spectroscopy. Replacement of Zr at the Ti site in the perovskite block is found from the increase in the lattice parameters as a function of Zr contents. Combined X‐ray diffraction patterns and Raman analysis suggested less than 40 mole% Zr solubility in Bi 4 Ti 3 O 12 . At 40 mole% of Zr substitution or above, the unreacted monoclinic‐phase ZrO 2 is observed in the X‐ray diffraction patterns and the Raman spectra. The incorporation of Zr in Bi 4 Ti 3 O 12 reduces the soft mode wavenumber and the transition temperature. Moreover, temperature dependent studies confirmed the ferroelectric to paraelectric transition in Bi 4 Ti 3 O 12 at about 675 °C. On increasing the Zr content up to 40% on the Ti sites of Bi 4 Ti 3 O 12 , a systematic decrease in the phase transition temperature from 675 to 630 °C was observed. Copyright © 2007 John Wiley & Sons, Ltd.