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High temperature X-ray investigation of liquid phase sintering of Zinc Oxide

Andreas Klimera 1Mohammad Lutful Arefin 1Friedrich Raether 

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


ZnO-based ceramics doped with M2O3 show highly non-ohmic current voltagebehaviour 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. In this work different compositions in the Zno-Bi2O3-Sb2O3-system were inwestigated.

High temperature in-situ X-ray diffraction by synchrotron source is used to observe successive formation of new phases during sintering. Partial evaporation of (Bi, Sb)2O3 leads to gradients in a liquid phase distribution in the surface region, so conventional HT-XRD is not reasonable because of its small penetration depht (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.


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Presentation: Poster at 11th European Powder Diffraction Conference, Poster session, by Andreas Klimera
See On-line Journal of 11th European Powder Diffraction Conference

Submitted: 2008-07-01 14:54
Revised:   2009-06-07 00:48