Microstructural and high-temperature impedance spectroscopy study of Ba6MNb9O30 (M=Ga, Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure

Andrei Rotaru, Finlay D. Morrison

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11 Citations (Scopus)
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Abstract

This work reports on the microstructural and high-temperature impedance spectroscopy study of a family of dielectric ceramics Ba6MNb9O30 (M=Ga, Sc, In) of tetragonal tungsten bronze (TTB) structure with relaxor properties. For Ba6GaNb9O30 and Ba6InNb9O30 pellets, the SEM images have revealed good, dense internal microstructures, with well-bonded grains and only discrete porosity; in contrast Ba6ScNb9O30 pellets had a poorer microstructure, with many small and poorly-bonded grains gathered in agglomerates, resulting in significant continuous porosity and poorly defined grain boundary regions. The electroactive regions were characterised by the bulk and grain boundaries capacitances and resistances, while their contribution to the electrical conduction process was estimated by determining activation energies from the temperature (Arrhenius) dependence of both electric conductivities and time constants. For Ga and In analogues the electronic conductivity are dominated by the bulk response, while for Sc analogue, the poorly defined grain boundaries give a bulk-like response, mixing with the main bulk contribution.
Original languageEnglish
Pages (from-to)11810-11821
Number of pages12
JournalCeramics International
Volume42
Issue number10
Early online date20 Apr 2016
DOIs
Publication statusPublished - 1 Aug 2016

Keywords

  • Electrical conduction
  • Grain boundary
  • High-temperature impedance spectroscopy
  • Microstructure
  • Relaxors
  • Tetragonal tungsten bronzes

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