Effects of BN dopant on electrical characteristics of barium-excessive BaTiO_3 ceramics for laminated positive temperature coefficient thermistors fabricated by tape casting technique

摘要

The barium-excessive BaTiO_3 ceramics with BN addition for laminated positive temperature coefficient (PTC) thermistors are fabricated. The tape casting technique and reduction/reoxidation process are employed into the fabricating procedure. The influences of BN additive on ceramic characteristics are discussed. The addition over 5% leads to rectangular and abnormal large grains. The 5% BN-doped ceramics shows a resistivity of 233 ?-cm and PTC jump of 3.4 orders of magnitude. The charge carrier density in grain bulk and acceptor state density at grain boundaries are evaluated. The correlation of BN doping amount with room temperature resistivity, PTC jump, reoxidation effect as well as charge carrier and acceptor state density are investigated.