| abstract |
It is an aggregate of particles of the compound represented by the following formula (1), and in the number-based particle size distribution measured by the laser diffraction / scattering method, the most frequent value is the mode diameter and the cumulative 10% diameter is D 10 . And when the cumulative 90% diameter is D 90 , the mode diameter is 5 μm or more and less than 10 μm, and (D 90 −D 10 ) / mode diameter ≤ 3.0. Its application. In formula (1), A represents at least one metal element selected from the group consisting of Sr, Ba, Ca, and Pb, and x satisfies 1.5 ≦ x ≦ 8.0. |