Patent ID: 7678188

Claim:
A method of producing superfine particles of a Prussian-blue-structure metal complex, comprising: (A) mixing an aqueous solution that comprises an anionic cyano-metal-complex having a metal atom M 1 as a central metal and an aqueous solution that comprises a metal cation of a metal atom M 2 , to precipitate crystals of a Prussian-blue-structure metal complex comprising the metal atom M 1 and the metal atom M 2 ; then (B) mixing the crystals of the Prussian-blue-structure metal complex and a solution of a ligand L dissolved into a solvent, to obtain a dispersion liquid containing superfine particles of the Prussian-blue-structure metal complex; and (C) separating the Prussian-blue-structure metal complex from the dispersion liquid for forming the superfine particles, wherein the ligand L is one or more amino-groups.