Observation of potential barriers on barium strontium titanate PTCR ceramics by electrostatic force microscopy

A composition of PTCR ceramic based in barium titanate with isovalent replacement of part of barium by strontium using lanthanum and manganese as additives was investigated. The transition temperature, typical of these materials, was shifted below the room temperature by the presence of strontium, whose behavior was detected by tests of DC resistivity and impedance spectroscopy. The observation of potential barriers at grain boundaries was possible through the technique of electrostatic force microscopy (EFM). The results also showed the presence of space charges in regions inside grains, possibly at subgrain boundaries. (author)