Patent ID: 7306751

Claim:
A method of manufacturing a crystalline superfine particle which emits light depending upon the time-rate-of-change of a stress applied thereto, comprising: dissolving metal ions of a metal for forming the crystalline superfine particle in water to form an aqueous phase; stably dispersing the aqueous phase with a surfactant in oil to form a molecular aggregate in which hydrophilic groups of surfactant molecules orient inward and hydrophobic groups thereof outward in a nonpolar solvent thus encapsulating said metal ions of a metal for forming the crystalline superfine particle inside an inverted micelle; conducting a hydrolytic or precipitation reaction to form superfine particles; and crystallizing the superfine particles to form crystalline superfine particles which emit light depending upon the time-rate-of-change of a stress applied thereto, wherein the crystalline superfine particles have a composition expressed by the general formula A x B y O z where 0.8≦x≦1.1 1.8≦y≦2.2 {(2x+3y)/2}−0.2<z<{2x+3y)/2}+0.2 A=Sr k Ba l Ca m Mg n (0≦k, l, m, n ≦1, k+1+m+n=1) B=Al 1−p D p (0≦p<1) D=Y q Ga r In t (0≦q, r, t ≦1, q+r+t=1), wherein the metal ions in the water contained in the molecular aggregate are ions of alkaline earth metal used as the component A and ions of a metal used as the component B in the general formula, wherein the ratio of the ions of the alkaline earth metal as the component A relative to the ions of the metal as the component B is in the range from 0.1 to 0.5, and wherein the crystalline superfine particles has a grain size in the range from 5 nm to 100 nm.