The pyrochlore with the composition Bi2FeTa2O9.5 was obtained by solid-phase synthesis. The electronic state and the nature of the local environment of iron atoms were studied by electron spin resonance (ESR) and Mossbauer spectroscopy. In the Bi2FeTa2O9.5 ESR spectra a dipolar-broadened line with g similar to 2.05 from Fe3+ ion clusters are observed. This line is the superposition of components with widths of about 150 and 400 mT. On the low-field wing of the band, there is a feature with g similar to 4.3 relating to trace amounts of isolated Fe3+ ions in an octahedral position with a strong rhombic distortion. The Mossbauer spectrum of the Bi2FeTa2O9.5 compound demonstrates a slightly asymmetric doublet. The form of the doublet is re-produced by a superposition of a doublet and a singlet. About 93% of the spectral area of the paramagnetic part of the spectrum falls on the Fe(III)-doublet with IS = 0.365 +/- 0.0020 mm/s, QS = 0.604 +/- 0.034 mm/s, correlated with Fe3+ ions in regular axial octahedral positions. The remaining part is represented by a Fe(III)singlet with IS = 0.176 +/- 0.0288 mm/s from Fe3+ ions in a symmetric environment. The electrical properties of the compound were studied at temperatures of 20 - 450 degrees C in the frequency range of 25 Hz - 1 MHz. It was found that synthesized ceramics exhibit dielectric properties. The permittivity and the dielectric loss tangent at 20 degrees C were determined and are 57 and 0.003 (1 MHz), respectively. (C) 2022 Published by Elsevier B.V.

Original languageEnglish
Article number163928
Number of pages6
JournalJournal of Alloys and Compounds
Volume903
Early online date22 Jan 2022
DOIs
StatePublished - 15 May 2022

    Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

    Research areas

  • pyrochlore, iron doping, ESR, Mössbauer spectroscopy, permittivity, Dielectric loss tangent, Iron doping, Pyrochlore, Permittivity, SYSTEM, NEXAFS, EPR, ELECTRICAL-PROPERTIES, SPECTROSCOPY, SUBSOLIDUS PHASE-EQUILIBRIA, Mossbauer spectroscopy, MAGNETIC-PROPERTIES, CERAMICS

ID: 91834891