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High Temperature in-situ X-ray Investigation of Liquid Phase Sintering of Zinc Oxide

Andreas Klimera ,  Mohammad Lutful Arefin ,  Friedrich Raether 

Fraunhofer ISC (ISC), Neunerplatz 2, Würzburg 97082, Germany


ZnO-based ceramics doped with M2O3 show highly non-ohmic current-voltage behaviour that is important for surge arresting in electrical circuitry. The addition of Bi2O3 to ZnO lowers melting temperature and promotes liquid-phase sintering. In contrast, the presence of Sb2O3 influences grain size distribution and the formation of new intermediate compounds. Grain boundary phases with spinel and pyrochlore structures affect the electrical behaviour of ZnO-based varistors.

High temperature in-situ X-ray diffraction by synchrotron source is used to monitor progressive formation of new phases during sintering. Partial evaporation of (Bi,Sb)2O3 leads to gradients away from sample surface in liquid phase distribution, so conventional HT-XRD is not reasonable because of its small penetration depth in the surface region (10-20 µm).

Therefore, synchrotron X-rays were used at the HASYLAB, Hamburg to analyze the phase formation in samples of 1 mm thickness. The samples were heated in a resistive furnace which was specially developed for those experiments and measured in transmission mode. Different compositions in the ZnO-Bi2O3-Sb2O3-system were investigated.


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium I, by Andreas Klimera
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-31 10:30
Revised:   2009-06-07 00:44