Curie Temperature of BaTiO3

The Curie point ( T C ) of BaTiO 3 was earlier reported to be 120° C and has been recently believed to be 130° C. Some experiments have been performed here to reconfirm the T C . Firing conditions used for preparing BaTiO 3 were examined first with the use of pure BaCO 3 or Ba(NO 3 ) 2 and TiO 2 . The x -dependence of T C in (BaO) 1- x (TiO 2 ) 1+ x solid solution was measured. Data were scattered and suffered from individual variations. According to probability considerations, T C of BaTiO 3 was evaluated from the intercept at x =0. On the other hand, composition dependence of T C in some related solid solution systems, (Ba 1- y Pb y )TiO 3 . (Ba 1- y Sr y )TiO 3 and (BaTiO 3 ) 1- y (KF) y , was examined and the T C of BaTiO 3 was estimated by extrapolation toward the limit y →0. In conclusion, the Curie point of BaTiO 3 is determined as 123.0±0.6° C.