Structural transformations and physical properties of (1 - X) Na0.5Bi0.5TiO3 - X BaTiO3 solid solutions near a morphotropic phase boundary

Hari Sankar Mohanty, Tapabrata Dam, Hitesh Borkar, Dhiren K. Pradhan, K. K. Mishra, Ashok Kumar, Balaram Sahoo, Pawan K. Kulriya, C. Cazorla, J. F. Scott, Dillip K. Pradhan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Piezoelectric and other physical properties are significantly enhanced at (or near) a morphotropic phase boundary (MPB) in ferroelectrics. MPB materials have attracted significant attention owing to both fundamental physics as well as the possibility of well-regulated energy and information storage devices which are dominated by lead (Pb)-based materials. Here, we report the crystal structure, Raman spectra, dielectric constant and polarization near the MPB of lead free (1 - x) Na0.5Bi0.5TiO3 - x BaTiO3 (0.00 x 0.10) solid-solution, prepared by sol-gel auto combustion technique and sintered by microwave sintering technique. With the addition of BaTiO3 into Na0.5Bi0.5TiO3, it induces a structural phase transition from R3c (a single phase) to R3c + P4mm (a dual phase) close to x = 0.06 and 0.07 and transform to a high symmetry tetragonal phase P4mm at higher compositions (x = 0.08 to 0.10) as evident from our x-ray Rietveld refinement and Raman spectroscopic results. We perform first-principles calculations based on density functional theory that confirm a structural transition from a rhombohedral to a tetragonal phase under increasing x. In the prepared solid solution, an anomalous enhancement of remnant polarization (2P0r) was observed for x = 0.06 and 0.07, which has been explained based on the existence of the MPB. On the other hand, the value of coercive field E0C was found to be decreased linearly from x = 0.00 to 0.06; it is constant for higher compositions. Further details of the ferroelectric properties on the electric field poled samples have been studied and compared with the as-grown (unpoled) samples.

Original languageEnglish
Article number075401
JournalJournal of Physics Condensed Matter
Volume31
Issue number7
DOIs
Publication statusPublished - 31 Dec 2018

Keywords

  • crystal structure
  • first-principles calculations
  • lead-free ferroelectric materials
  • microwave sintering
  • morphotropic phase boundary
  • NBT-BT solid solution

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