Application of Forced Electrification for Preparation of Complex Particles

The purposes of the present work are to describe the importance of the application of forced electrification on complex particle preparation and to develop new materials with multiple functions by combining two kinds of particles electrified reciprocally. This paper reports a preparation method and the positive temperature coefficient of resistivity (PTCR) characteristics of composites consisting of semiconductive BaTiO ₃ particles and metallic indium powder. The forced electrification technique was applied to a complex particle preparation process and confirmed to be effective as follows: 1. A vibrating cylindrical electrode can force-electrify metal, semiconductor and insulator particles with positive or negative charges. 2. When two kinds of particles electrified reciprocally are mixed in the same region at the same time, complex particles can be produced by the electrostatically attractive force working between them. 3. Indium-semiconductive BaTiO ₃ complex particles made with this processing offer a new PTCR material which can be used in arbitrary shapes by simple packing. This behavior cannot be accomplished by the conventionally sintered PTCR materials.