Effect of Solvothermal Reaction-Time on Microstructure and Microwave Absorption Properties of Cobalt Ferrite

Cobalt ferrite is synthesized via a simple solvothermal method. Then, the effect of the degree of cobalt-ferrite growth on its morphology, structure, electromagnetic performance, and microwave absorption is studied as a function of the solvothermal reaction time. When the reaction time during synthesis is 8 h, the structure of cobalt ferrite is hollow spheres. In addition, when the reaction time is 12 h and 16 h, it becomes a submicron sphere with a diameter of 100–150 nm. With the increase of reaction time, cobalt ferrite underwent the process of cobalt ferrite formation, hollow structure formation, hollow structure disappearance, agglomeration separation and reagglomeration in 4–16 h. In general, CoFe(2)O(4)-8h shows better microwave absorption-the effective absorption bandwidth is 9.84 GHz (6–15.84 GHz) for a thickness of 1.72–3.72 mm. This represents a minimum return loss of −47.24 dB. A better understanding of both the synthesis parameters and the relationship between structure and electromagnetic properties can open new possibilities for applications and the development of microwave absorbing materials.