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R K  Dwivedi, Speaker at Materials Science and Engineering Events
Department of Physics and Materials Science & Engineering, JIIT Noida, India
Title : Compositionally driven polarization and structural transitions in PZT substituted BiFeO3 ceramics


In recent years, BiFeO3 has shown fascinating properties due to its multistage data storage characteristics and PbZrTiO3 is already known to be one of the best piezoelectric materials so far.  In view of this, an effort has been made to synthesize solid solution formation between PbZr0.52Ti0.48O3 (PZT) and BiFeO3 (BFO). X-ray diffraction studies have revealed the solid solution formation over the entire range of compositions with the intermediate structural phase transitions from Rhombohedral (R3C) for x = 0.0 to 0.10, Monoclinic (CC) for x = 0.20 to 0.40, Monoclinic (Cm) for x = 0.50 to 0.70, co-existence of Monoclinic and Tetragonal (Cm+P4mm) for x = 0.70 to 0.90 and Tetragonal for x = 1.0.  It is further envisaged that with substitution of PZT, the polarization vector Ps oriented along <111> for x = 0.0 (R3C symmetry), rotates along <100> direction (P4mm symmetry) for x = 1.0 via <110> direction for intermediate values of x i.e. monoclinic phases of Cc and Cm types. Dielectric constant vs temperature plots have shown multiple anomalies at different temperatures with increasing x. The low temperature anomalies are found to occur due to complex defect dipoles formation in these materials and high temperature anomaly is attributed to the intrinsic characteristic of the end members. Dielectric constant has been found to increase and dielectric loss has been found to be decreased with increasing x. A significant decrease in current density with x within the applied electric field up to 4kV/cm has witnessed reduced losses in these materials. Remanent polarization has been found to increase with x, however, remanent magnetization increases with x up to x = 0.30 and thereafter decreases. The decrease in magnetization beyond x = 0.30 may be attributed to the annihilation of spiral spin structure of BFO due to foreign element of do character at Fe sites in BFO.

What will audience learn from your presentation?

  • Concept of polarization rotation with structural changes. Structure and property correlation in multiferroics.
  • Faculty can learn to use the concept to carryforward the research in this. Since work is pure experimental, so it is a practical solution for them. It may definitely help in designing new problems.


Dr. R.K. Dwivedi did M. Tech. in Materials Technology in 1994 followed by Ph.D. in Materials Science and Technology in 1999 from Indian Institute of Technology Banaras Hindu University, India. After completing Ph.D., Dr. Dwivedi joined the group of Prof. D. Bahadur, as a post doct fellow in the Department of Metallurgical Engineering and Materials Science, IIT Bombay India.  Dr. Dwivedi has joined JIIT Noida India as a faculty in 2005. He has published more than 80 quality papers and has delivered more than two dozen talks in national and international conferences.