The influence of different additives and the mode of their addition on the sintering behavior and the properties of semiconducting barium titanate ceramics |
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| Institution: | 1. Marshall Space Flight Center, Huntsville, AL 35812, USA;2. Micron School of Materials Science and Engineering, Boise State University, Boise, ID 83725, USA;3. Center for Advanced Energy Studies, Idaho Falls, ID 83401, USA;1. Laboratory of Analytical Chemistry and Applied Ecochemistry, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium;2. Particle and Interfacial Technology Group, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium;1. Belgian Ceramic Research Centre (Member of EMRA), Avenue Gouverneur Cornez 4, Mons, B-7000 Belgium;2. MTM KULeuven, Kasteelpark Arenberg 44, Leuven, B-3001 Belgium;3. EMPA UCLouvain, Place Sainte Barbe 2, Louvain-la-Neuve, B-1348 Belgium;1. Université François-Rabelais de Tours, GREMAN UMR 7347 CNRS, Tours, France;2. Univ. Lille, CNRS, Centrale Lille, ISEN, Univ. Valenciennes, UMR 8520 - IEMN, F-59000 Lille, France;1. Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de Blois, 15 rue de la chocolaterie, CS 2903, F-41029 Blois Cedex, France;2. Université Paris 13, Sorbonne Paris Cite, Laboratoire des Sciences des Procédés et des Matériaux, CNRS, UPR 3407, 99 avenue Jean Baptiste Clément, F-93430 Villetaneuse, France |
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| Abstract: | The influence of different additives (TiO2, TiO2/SiO2, CaO/TiO2/SiO2, 2BaO/TiO2/2SiO2) and the mode of their incorporation (spray drying: series 1; mixed-oxide method: series 2) on the sintering behavior and the microstructural and electrical properties of n-doped BaTiO3 ceramics has been investigated. The incorporation of the additives from their aqueous solution by spray drying produces a homogeneous distribution of the additive in the BaTiO3 matrix powder by coating the BaTiO3 particles. This homogeneous distribution significantly lowers the activation energy for the densification process compared with that of the powders of series 2. Dynamic and isothermal dilatometric measurements revealed that the sintering process is considered as a classical solid phase sintering followed by recrystallization of the BaTiO3 matrix particles by a eutectic melt. The densification process is dominated by sliding processes. These sliding processes are caused by the amorphous layer of the additive and by the defect-rich grain boundary layers of the BaTiO3 grains generated intermediately by diffusion processes and reactions of the matrix material with the additive forming the secondary phases Ba2TiSi2O8 and Ba4Ti13O30, respectively. In series 1, ceramics with a homogeneous microstructure and useful electrical properties (e.g. low resistivity at room temperature) were already produced at a sintering temperature of 1280°C (with SiO2-containing additives) due to the homogeneous distribution of the additive. The ceramics of series 2 sintered at the same temperature could only be obtained in poor quality. At higher sintering temperatures the differences between the two series vanished. |
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