Dielectric performance of pyrochlore-type Bi2MgNb2-xTaxO9 ceramics: The effects of tantalum doping

N. A. Zhuk, M. G. Krzhizhanovskaya, N. A. Sekushin, V. V. Kharton, B. A. Makeev, V. A. Belyy, R. I. Korolev

Research output: Contribution to journalArticlepeer-review


The solid solutions based on the pyrochlore-type system Bi2MgNb2-xTaxO9 were formed in the compositional range х = 0–2.0 (Bi1·6Mg0·8Nb1.6-tTatO7.2, t = 0–1.6). The Rietveld method was used to refine the structure for Bi2MgNb2-xTaxO9 (x = 0, 1.0, 2.0). The increasing tantalum content led to the slight decrease in the cubic unit cell parameters from 10.56934 (4) Å for x = 0 and 10.54607 (3) Å for x = 2 (sp.gr. Fd-3m:2). At the same time, tantalum additions suppressed grain growth in the pyrochlore ceramics during sintering and made it possible to obtain materials with an average grain size of 1–2 μm (Bi1·6Mg0·8Ta1·6O7.2). The increase in the Ta5+ concentration led to the decrease in the dielectric permeability from 104 (Bi1·6Mg0·8Nb1·6O7.2) to 20 (Bi1·6Mg0·8Ta1·6O7.2) at room temperature, while the dielectric loss tangent remained lower than 0.002, which is due to the small grain size and the high porosity of the samples. An increase in temperature has practically no effect on the values of the dielectric permittivity in the entire frequency range. The samples have weak through conductivity. The activation energies of electrical conductivity varied in the range of 0.84–1.00 eV, and the less tantalum, the lower the activation energy. The electrical properties of the samples at 200 Hz to 1 MHz are described by the simplest parallel scheme.

Original languageEnglish
JournalCeramics International
StateE-pub ahead of print - 29 Mar 2021

Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Materials Chemistry


  • Bismuth niobate
  • Bismuth tantalate
  • Ceramics
  • Dielectric properties
  • Microstructure
  • Pyrochlore

Fingerprint Dive into the research topics of 'Dielectric performance of pyrochlore-type Bi<sub>2</sub>MgNb<sub>2-x</sub>Ta<sub>x</sub>O<sub>9</sub> ceramics: The effects of tantalum doping'. Together they form a unique fingerprint.

Cite this