| abstract |
A Bi 12 XO 20 powder, wherein X represents at least one kind of element selected from the group consisting of Si, Ge, and Ti, is produced by a process comprising: a step (A) of preparing a solution containing the Bi element and a solution containing the X element, a step (B) of adding the two kinds of the solutions to a mother liquor having been previously fed into a reaction chamber, a mixed liquid being thereby prepared, and a step (C) of raising a temperature of the mixed liquid from the temperature, at which the addition is begun. In the step (B), the addition of the two kinds of the solutions is performed such that the substance quantities of the Bi element and the X element in the mixed liquid increase in parallel from the time at which the addition is begun. |