The electrical properties and microstructure of fluorine-doped BaTi03 ceramics have been studied. The samples were prepared using a classical ceramic technology that involved the calcination of intimately mixed powders of BaCO3, Ti02, and BaF2. When the samples were sintered in untreated ambient air, the fluorine from the sample reacted with water vapour and formed gaseous HA. To prevent this hydrolysis of the fluorine, the samples were sintered in dried air. The fluorine-doped BaTi03 ceramics sintered in a dry atmosphere showed microstructure and electrical properties typical of donor-doped BaTi03. The samples containing up to 0.3 mol% of fluorine were coarse-grained, semiconducting, and displayed a remarkable PTCR effect. In contrast, samples with a higher fluorine concentration were fine grained and insulating.
