Fabrication of lead-free semiconducting ceramics using a BaTiO 3-(Bi1/2Na1/2)TiO3 system by adding CaO

Abstract

BaTiO3( Bi1/2Na1/2)TiO3 (abbreviated as BTBNT) 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 BTBNT ceramics showed semiconducting behavior with the resistivity at room temperature ρRT = 103ωcm and a resistivity change near Curie temperature. Chemical composition analysis suggested that Ca2+ acted as a donor by substituting for Na+ in the BTBNT ceramics. © 2011 The Ceramic Society of Japan.