added thereto to prepare the aqueous solution of 1 l while being stirred this aqueous solution was reacted at 100 u00b0 c for four hours the resultant precipitate was rinsed by water by decantation filtered further rinsed by water and then dried at 100 u00b0 c for all day long the x ray diffraction pattern of the fine particle powder obtained by the above treatment was substantially the same as that shown in fig1 and it was confirmed that this fine powder was ba 2 3 sr 1 3 tio 3 further according to the transmission electron microscope the fine powder of substantially the same shape as that in fig3 was observed the lattice constant a 0 of the fine powder was 3 981 u00e5 50 g of ticl 4 was dissolved into 50 ml of an iced water while being stirred so as to make a ti aqueous solution then water was added thereto to prepare the aqueous solution of 500 ml then 34 44 g of ba no 3 2 and 27 89 g of sr no 3 2 were added and dissolved into this aqueous solution thereafter the aqueous solution was adjusted to have a ph 14 by adding a koh solution thereto and water was added thereto to prepare the aqueous solution of 1 l while being stirred this aqueous solution was reacted at 100.