稲熊 宜之

The oxygen nonstoichiometry in the high T_c superconductor Ba_2SmCu_3O_<7-x> was determined over the temperature range of 350° to 900℃ under the oxygen partial pressure between 10^<-3> and 1 atm, with the thermogravimetric measurement calibrated by the iodometric titration technique. The temperature dependency of the nonstoichiometry indicates that a phase transition occurs at a temperature between 600°and 700℃.