Method for producing metal oxide nanoparticles

A method for producing metal oxide nanoparticles comprising:

• a first step of preparing a reaction solution containing a metal complex, an alcohol, and water,
• a second step of heating the reaction solution for phase-separation under a hermetically sealed atmosphere where a volumetric expansion ratio of the reaction solution reaches 5 to 15%,
• a third step of holding the reaction solution heated in the second step for 12 hours or more for dehydrating the metal complex to precipitate the metal oxide nanoparticles, and
• a fourth step of collecting the metal oxide nanoparticles after the metal oxide nanoparticles are cooled,
• wherein the phase-separation of the reaction solution proceeds in two stages of clouding of the reaction solution and clarifying of the clouded reaction solution,
• a holding temperature under the hermetically sealed atmosphere is 130 to 190° C. in the third step,
• the metal complex is prepared by allowing a metal salt containing at least one metal to react with a compound to be a ligand for the metal salt in an aqueous solution,
• the at least one metal is selected from copper, nickel, cobalt, zinc, iron, cerium, titanium, silver, palladium, molybdenum, niobium, and zirconium, and
• the ligand includes ammonia, urea, thiourea, thiosulfuric acid or cyanides.