Dielectric responses in polycrystalline rare-earth iron garnets

Yu Jhan Siao, Xiaoding Qi

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Rare-earth iron garnets (RIG, R = Y, Tb and Lu) were sintered at 1350 °C. Their crystal structures were refined by the Rietveld method, which showed that the oxygen coordination polyhedra were highly distorted. X-ray photoelectron spectroscopy revealed a similar Fe2+/Fe3+ratio (∼27/73) in different RIGs. The origins of dielectric responses were identified by cross examination of the permittivity, modulus and impedance presentations. Fitting experimental data with the Debye-type and Maxwell-Wagner models revealed that the dielectric relaxation at room temperature was dominated by the Debye-type process but as temperature increased, the Maxwell-Wagner effect gradually took over. The static permittivity was 750, 785 and 2653 for YIG, TbIG and LuIG, respectively. The particularly large permittivity of LuIG arose from a large difference between the distortions of FeO6and FeO4in the structure and therefore, a large dipole moment was created when electron hopping between the octahedral and tetrahedral sites took place.

Original languageEnglish
Pages (from-to)672-682
Number of pages11
JournalJournal of Alloys and Compounds
Volume691
DOIs
Publication statusPublished - 2017 Jan 1

All Science Journal Classification (ASJC) codes

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

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