Features of the synthesis and the study of nanocrystalline cobalt-nickel spinel

A nanocrystalline compound nickel cobaltite (NiCo 2 O 4 ) with the average size of crystals of ∼20 nm at 700°C has been synthesized using the method of combined crystallization of solutions of nitrates with the subsequent thermal and ultrasonic treatment. The optimal sintering mode of the NiCo 2 O 4 powder (1300°C, 2 h, air) has been selected, and ceramics (60–65 nm) with open porosity of 25–30% have been prepared. The temperature and frequency dependences of the electrical conductivity of nickel cobaltite have been studied. It has been assumed that the high values of the electrical conduction and pseudo-capacity of NiCo 2 O 4 are due to the variable valence of Ni and Co in oxides. It is recommended to use cobaltite nickel as an electrode material of a supercapacitor and a catalyst of the oxygen isolation in fuel elements.