Revealing the influence of Nb-doping on the crystal structure and electromechanical properties of (K, Bi)(Mg, Ti, Nb)O3 ceramics

Aurang Zeb, Fazli Akram, Muhammad Habib, Qamar Iqbal, Amir Ullah, Ihsan Ullah, Nasir Ali, S. J. Milne, Muhammad Sheeraz, Conrad Ingram, Shahid Iqbal, Fayaz Hussain, Adnan Younis, P. T. Tho, Chang Won Ahn

Research output: Contribution to journalArticlepeer-review


Nb-modified lead-free ceramics (K0.48Bi0.52)(Mg0.02Ti0.98−xNb x)O3, (KBT-BMTNbx with x = 0.00 − 0.05) were synthesized by a conventional solid-state reaction route followed by furnace cooling. The effects of Nb-doping on the structural properties and electrical properties of KBT-BMTNbx ceramics have been investigated. The X-ray diffraction pattern indicates a mixed tetragonal and cubic phase for the pure KBT-BMTNbx ceramics. Therefore, a large piezoelectric actuator coefficient d 33* ≈ 700 pm/V, piezoelectric sensor coefficient (d 33 ≈ 133 pC/N) along with remnant polarization (P r ≈ 17.5 µC/cm2), maximum electromechanical strain ≈ 0.35% and maximum temperature (T m ≈ 336 ºC) were obtained for KBT-BMTNbx. However, with Nb-doping, a compositionally driven phase transformation occurred from mixed rhombohedral and tetragonal phases to cubic phase. Because of the excess Nb-doping in the KBT-BMT ceramics, the grain size suddenly decreased, as a result, the long-range ferroelectric phase was converted into a short-range relaxor phase. Hence, a low dielectric loss tanδ ≈ 0.02 was achieved at x = 0.02 composition. This superior dielectric performance is correlated to the crystal structure morphotropic phase boundary, optimum grain size (≈ 2 μm), maximum lattice distortion, and soft-ferroelectric effect induced by the donor doping. The main aim of recent research is to investigate P r, d 33, d 33*, S max, and reduced tanδ for practical applications in the real world.

Original languageEnglish
Pages (from-to)122-132
Number of pages11
JournalJournal of Electroceramics
Issue number2
Publication statusPublished - Oct 2023
Externally publishedYes


  • Electromechanical properties
  • Lead-free ceramics
  • Morphotropic phase boundary
  • Nb-doping
  • Relaxor-ferroelectric

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Mechanics of Materials
  • Materials Chemistry
  • Electrical and Electronic Engineering


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