Composite indium oxide particle, method for producing same, conductive coating material, conductive coating film, and conductive sheet

A zinc compound is mixed into an alkaline solution wherein a tin salt is dissolved and an aqueous solution of an indium salt is added thereto. The obtained hydroxide or hydrate containing tin, indium and zinc is subjected to a heat treatment at a temperature within the range of 110-300{C in the presence of water. Then after filtration and drying, the thus-obtained material is subjected to another heat treatment at a temperature within the range of 300-1000{C in the air, and further subjected to a reduction treatment at a temperature within the range of 150-400{C in a reducing atmosphere, thereby forming zinc oxide-tin containing indium oxide composite particles. With this method there can be obtained zinc oxide-tin containing indium oxide particles having an average particle diameter from 5 nm to 100 nm. The thus-obtained zinc oxide-tin containing indium oxide composite particles are suitable for formation of a transparent conductive coating film having ultraviolet-shielding properties.