Micro‐Raman study of Zr‐substituted Bi4Ti3O12 ceramics

We have studied the lattice vibrational modes of Zr‐substituted Bi₄Ti₃O₁₂ 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 Bi₄Ti₃O₁₂. At 40 mole% of Zr substitution or above, the unreacted monoclinic‐phase ZrO₂ is observed in the X‐ray diffraction patterns and the Raman spectra. The incorporation of Zr in Bi₄Ti₃O₁₂ reduces the soft mode wavenumber and the transition temperature. Moreover, temperature dependent studies confirmed the ferroelectric to paraelectric transition in Bi₄Ti₃O₁₂ at about 675 °C. On increasing the Zr content up to 40% on the Ti sites of Bi₄Ti₃O₁₂, a systematic decrease in the phase transition temperature from 675 to 630 °C was observed. Copyright © 2007 John Wiley & Sons, Ltd.