Papers by Author: Joanna Warycha

Abstract: Varistors obtained by sintering zinc oxide with additives were investigated. In this work the crystalline microstructure of ZnO varistor body is studied by X-ray diffraction method, before and after additional annealing. The crystalline microstructure is characterised by the prevalent crystallite shape, the volume-weighted crystallite size distribution, the second-order crystalline lattice strain distribution and the derivative quantities. The evolution of these characteristics, particularly of bimodal size distribution, elucidate some details of the formation of crystalline zinc oxide and provide additional arguments for explaining the change of the electric characteristics of varistors induced by annealing.

Abstract: In this work the laboratory–scale installation for synthesising powder materials with nano-size grains is presented. Nano-sized zinc and tin oxides were obtained using the spraypyrolysis (SP) method. The zinc oxide was derived from zinc acetate at 300oC, 430oC, 580 oC, 800oC and 950oC. The tin oxide was processed by the thermal decomposition of tin tartrate at 500oC. The SP synthesized zinc oxide was used for manufacturing a methane sensor which was characterized as possessing a much wider range of operating and substantially higher sensitivity, 10 times higher, to methane gas compared to a sensor made out of commercially available zinc oxide.