ZIRCONIUM OXIDE HYDRATE PARTICLE AND METHOD FOR PRODUCING THE SAME

PROBLEM TO BE SOLVED: To provide zirconium oxide hydrate particles having a large amount of hydrated water, high proton conductivity, and favorable dispersion performance. SOLUTION: The zirconium oxide hydrate particles are represented by general formula: ZrO2-nH2O, and characterized in that the average primary particle diameter is 0.5-5 nm, the average secondary particle diameter is ≤100 nm, and n in the general formula is a number of 2.5-10. A method for producing the zirconium oxide hydrate particles comprises the steps of: producing zirconium oxide hydrate particles by mixing an aqueous solution of a zirconium salt and an aqueous alkali solution and adjusting the pH to 7.0 to 13.0; and subjecting the zirconium oxide hydrate particles to a microwave-hydrothermal treatment in the presence of water for a time of 1 to