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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1. High Temperature in-situ X-ray Investigation of Liquid Phase Sintering of Zinc Oxide
2. Concentration dependent fluorescence lifetime in nanocrystalline Y₂O₃:Eu phosphors