Fabrication of lead-free semiconducting ceramics using a BaTiO₃–(Bi_1/2Na_1/2)TiO₃ system by adding CaO

抄録

BaTiO₃–(Bi_1/2Na_1/2)TiO₃ (abbreviated as BT–BNT) solid solution semiconducting ceramics, as a candidate for a lead-free PTC (Positive Temperature Coefficient of resistivity) thermistor usable over 130°C, were synthesized by adding CaO into the calcined powder. The CaO added BT–BNT ceramics showed semiconducting behavior with the resistivity at room temperature ρ_RT = 10³ Ω cm and a resistivity change near Curie temperature. Chemical composition analysis suggested that Ca²⁺ acted as a donor by substituting for Na⁺ in the BT–BNT ceramics.