Synthesis of cobalt-aluminate spinels by ultrasonic assisted electroless plating

Co/Al_2O_3 composite powder was prepared by ultrasonic assisted electroless plating and cobalt aluminate spinel powder was obtained by calcining the composite powder at 1200℃ for 1.5h.The morphology,composition and crystalline structure were characterized by SEM,TEM and XRD.The results show that the Co/Al_2O_3 composite powder consists of Co and Al_2O_3 phases,and the Co phase with a loose structure distributing uniformly at the surface of Al_2O_3 particles clads the Al_2O_3 phase.At about 850℃,the composite transforms into spinel structure and the transformed product is also one kind of composite powder which consists of Al_2O_3 and CoAl_2O_4 phases with the from of α-Al_2O_3 particles wrapped by spinel CoAl_2O_4 on their surface.