Interface-assisted synthesis of the Mn3-xFexO4 gradient film with multifunctional properties

Anisotropic gradient materials are considered as promising and novel in that they have numerous functional properties and are able to transform into hierarchical micro-structures. We report a facile method of gradient inorganic thin film synthesis through diffusion-controlled deposition at the gas-solution interface. To investigate the reaction of interfacial phase boundary controllable hydrolysis by gaseous ammonium, an aqueous solution of FeCl3 and MnCl2 was chosen as the precipitation pHs for the hydroxides of these metals differ gradually. As a result of synthesis using the Gas-Solution Interface Technique (GSIT) a thin film is formed on the surface of the solution that consists of Mn2+(Fe,Mn)3+2О4 nanoparticles with hausmannite crystal structure. The ratio between iron and manganese in the film can be adjusted over a wide range by varying the synthetic procedure. Specific conditions are determined that allow the formation of a Mn-Fe mixed oxide film with a gradient of composition, morphology and prop...