Abstract: Positive Temperature Coefficient of Resistivity (PTCR) materials based on Yttrium and Yttrium Fluoride (YF₃) doped Barium titanate (BaTiO₃) ceramics were prepared in different sintering atmospheres, respectively. The effects of
sintering atmospheres on the microstructure, property and mechanism of substitution of doped BaTiO₃ ceramics were investigated by the means of XRD, SEM, XRF
and R-T measuring instrument. Sintering in a low oxygen partial atmosphere can increase the densities of Y and YF₃ doped BaTiO₃ and make grain particle
grow. Both Y and YF₃ doped BaTiO₃ ceramics are n-type semiconductor in which Y substitutes A-site and F substitutes O-site. Sintered in a argon
atmosphere, Y doped BaTiO₃ exhibited little PTCR effect, however, an anomalous PTCR effect was observed when 0.3mol% YF₃doped BaTiO₃ ceramics was fired
in Argon atmosphere. This phenomenon may be explained by a new O site substitution mechanism.

Key words: barium titanate, PTCR effect, sintering atmosphere, substitution