Synthesis, Structure and Electrical Properties of Donor Doped Barium Titanate Ceramics

Johannes Hofer

Research output: ThesisDoctoral Thesis

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Abstract

In this work net-donor doped barium titanate ceramics were studied with impedance spectroscopy in the temperature range of 50 – 400 °C, SEM-EDX, XRD and TG-MS. A modified solid oxide route was applied to synthesize disk like ceramic samples showing a micro-scale microstructure and the PTCR-effect. PTCR-curves were measured with impedance spectroscopy, which led to a good separation of bulk-resistivities, grain boundary-resistivities and grain boundary capacitances. A variation of the DC-bias and the AC-amplitude showed the dependence of the electrical resistance of the samples on the applied electric field. Impedance spectroscopy was also applied on industrial PTCR ceramic samples. A variation of DC-bias, AC-amplitude, geometry, sinter-parameters, pO2 and reduction-oxidation experiments led to further insight to the characteristics of the material. The last part of the work dealt with the synthesis of submicron ceramic samples via a nanoscale precursor obtained by an oxalate precipitation route and low temperature calcination. This product was characterized in a temperature range of 50 – 400 °C. No PTCR-effect could be found in this oxalate-precursor product. However, the trapping energy for the Manganese dopant could be determined.
Translated title of the contributionSynthese, Struktur und Elektrische Eigenschaften von Donor Dotierten Bariumtitanat Keramiken
Original languageEnglish
QualificationDr.mont.
Supervisors/Advisors
  • Reichmann, Klaus, Assessor B (external), External person
  • Preis, Wolfgang, Assessor A (internal)
Publication statusPublished - 2016

Bibliographical note

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Keywords

  • Donor doped barium titanate
  • Impedance spectroscopy
  • PTC-effect
  • Interfacially controlled electroceramics
  • Grain boundaries
  • Electrical properties
  • Nanosynthesis
  • Oxalate route
  • Solid oxid route

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