TY - BOOK

T1 - Synthesis, Structure and Electrical Properties of Donor Doped Barium Titanate Ceramics

AU - Hofer, Johannes

N1 - no embargo

PY - 2016

Y1 - 2016

N2 - 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.

AB - 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.

KW - Donor doped barium titanate

KW - Impedance spectroscopy

KW - PTC-effect

KW - Interfacially controlled electroceramics

KW - Grain boundaries

KW - Electrical properties

KW - Nanosynthesis

KW - Oxalate route

KW - Solid oxid route

KW - Donor dotiertes Bariumtitanat

KW - Impdedanzspektroskopie

KW - PTC-Effekt

KW - Grenzflächenkontrollierte Elektrokeramiken

KW - Korngrenzen

KW - Elektrische Eigenschaften

KW - Nanosynthese

KW - Oxalat-Route

KW - Festoxid Route

M3 - Doctoral Thesis

ER -