Fabrication of PTC Sheet with Semiconducting BaTiO_3 Particles
A mono-layer sheet of 24 mm×24 mm and a multi-layer sheet of 12 mm×12 mm were fabricated as follows. Semiconducting BaTiO<SUB>3</SUB> particles were packed between two electrodes of aluminum foil. As the particles and electrodes were enclosed in a plastic bag, evacuated and heat-sealed, they were fixed and compressed by atmospheric pressure. One layer is formed by the packed particles in the mono-layer sheet, and two to three layers are formed in the multi-layer sheet. The particles are semiconducting BaTiO<SUB>3</SUB> for the mono-layer sheet and composite particles of semiconducting BaTiO<SUB>3</SUB> and In for the multi-layer sheet. Indium particles always exist between the semiconducting BaTiO<SUB>3</SUB> particles in the multi-layer sheet and lower the contact resistance between the semiconducting particles. The properties of the sheets are investigated and the following results are obtained. (1) Both the mono-layer sheet and the multi-layer sheet are flexible and show the PTC property. (2) The performance of the multi-layer sheets is almost the same with that of the mono-layer sheet. (3) The apparent resistance is higher than that of the sintered disk, because of the imperfect contact in the sheet. (4) The thickness is about 1.1 mm and it is thinner than commercial thin PTC plates.
- Materials transactions
Materials transactions 43(5), 956-960, 2002-05-01