Effects of metal contents ( Ni| Mn) and processing on PTCR ceramic properties

In order to obtain a low resistivity and high PTC effect , the Ni/ Mn/ BaTiO₃ composite was prepared bythe t raditional solid-crystal sintering method. The effect s of metal content s (Ni , Mn) and heat t reatment techniqueson positive temperature coefficient resistor ( PTCR) ceramic properties were studied. The very weak PTC effect ofthe composite sintered in deoxidizing atmosphere (1250 ℃, 20 min) was renewed effectively by heat-t reatment in air(780 ℃, 60 min) . The Ni/ Mn/ BaTiO₃ composite has the low room-temperature resistivity (ρ25 ℃ = 10. 2Ω·cm) andan obvious PTC effect (ρmax /ρmin = 1. 42 ×10³ ) .