Structural Distortions and Behavioural Changes in Phase Transition of Aurivillius Type Sr_1-xPb_xBi₂Nb₂O₉ Ferroelectric

In this paper effects of lead doping on the lattice response and phase transitions of bismuth-layered structure Sr_1−xPb_x Bi₂Nb₂O₉ (x = 0.0 to 0.5 in steps of 0.1) ferroelectric ceramic are reported. It is observed that structure attains more tetragonality with doping of lead up to 40%. Increased orthorhombic distortion is also observed. Curie temperatures of all samples were measured and the phase transition is explained in terms of lattice response of these ceramics. Sample with x = 0.5 shows decreased tetragonal strain and Curie temperature. Also, relationship of polarization with lattice response is discussed.

Keywords:

• Ferroelectrics
• lattice distortion
• phase transition

Acknowledgments

Authors thank Prof. T. C. Goel, Dept. of Physics, Indian Institute of Technology, New Delhi for making available experimental facility.

Paper originally presented at AMF-4, Bangalore, India, December 12-15, 2003.