The influence of the milling liquid on the properties of barium titanate powders and ceramics

• Published in: Journal of materials chemistry Vol. 7; no. 3; pp. 487 - 492
• Main Authors: ABICHT, H.-P, VÖLTZKE, D, RÖDER, A, SCHNEIDER, R, WOLTERSDORF, J
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 1997
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Electrotechnical and electronic ceramics; Exact sciences and technology; Technical ceramics; Wet grinding; Electrical conductivity; Electrical properties; Barium Titanates; Manufacturing; Experimental study; Oxide ceramics; Powder; Dielectric ceramics; Electroceramics
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/a604730k

The influence of the milling liquid on the properties of donor-doped (La3+) semiconducting BaTiO3 ceramics formed by the mixed oxide technique was investigated. Distilled water and propan-2-ol were used as milling liquids. Water was found to have two essential effects. First, it dissolves Ba2+ ions out of BaTiO3 grains, thus creating core-shell structures which were confirmed by HREM and EELS. They consist of a 3-5 nm thick TiOx-rich layer followed by a layer (about 10 nm thick) with a molar Ba/Ti ratio increasing from 0 to 1. These core-shell structures of the BaTiO3 powder positively affect the sintering behaviour of the greens by the high reactivity of the Ti-rich interlayer. Secondly, water cleans the BaTiO3 powder of acceptor contaminants, producing ceramics with a low electrical resistivity at room temperature. Propan-2-ol-milled ceramics of a comparable composition show a resistivity up to six orders of magnitude higher, owing to the compensation of La3+-doping by acceptor contaminants. 16 refs.