The Curie point (T-C) of BaTiO3 was earlier reported to be 120 degrees C and has been recently believed to be 130 degrees C. Some experiments have been performed here to reconfirm the T-C. Firing conditions used for preparing BaTiO3 were examined first with the use of pure BaCO3 or Ba(NO3)(2) and TiO2. The x-dependence of T-C in (BaO)(1-x)(TiO2)(1+x) solid solution was measured. Data were scattered and suffered from individual variations. According to probability considerations, T-C of BaTiO3 was evaluated from the intercept at x=0. On the other hand, composition dependence of T-C in some related solid solution systems, (Ba1-yPby)TiO3. (Ba1-ySry)TiO3 and (BaTiO3)(1-y)(KF)(y), was examined and the T-C of BaTiO3 was estimated by extrapolation toward the limit y-->0. In conclusion, the Curie point of BaTiO3 is determined as 123.0+/-0.6 degrees C.
