Abstract: A novel electroconductive zinc oxide powder which comprises zinc oxide and, being present as a solid solution formed with the zinc oxide, 0.01 to 10 mass % relative to the zinc oxide of at least one element selected from the group consisting of IIIB Group elements, IVB Group elements and Fe, has an average primary particle diameter of 0.03 ?m or less as calculated from its specific surface area, a bulk density of 0.20 g/ml or less and a volume resistivity of 1010 ?·cm or less; and a method useful for producing the electroconductive zinc oxide powder. The zinc oxide powder exhibits distinguished dispersibility when incorporated into a rubber, a resin or the like as an electroconductivity imparting agent, and thus can provide a material having a reduced electric resistance.

Abstract: Two or more substances are flowed from different inflow passages, and collided against each other at a flow rate of 4 m/sec or higher to cause a uniform reaction with each other for a short time. This method is advantageous for producing a dispersion liquid containing very fine particles the size of submicrons.

Abstract: In a fine particle producing device, particles of a substance contained in a fluid are caused to collide with each other under extremely high pressure, whereby the particles are emulsified, dispersed or reduced to finer particles in the fluid in an instant. One of the blocks mounted in a cylindrical sealed casing has a pair of curved channel portions for guiding converging high-speed fluid streams and a turbulence pocket formed at a position where the curved channel portions are joined for temporarily holding fluid turbulence caused by collision of the high-speed fluid streams.