(710d) Synthesis of Zinc Ferrites for Thermochemical Water-Splitting

Two methods have been employed to synthesize zinc ferrite materials using metal precursors (nitrates) and various carbonaceous fuels (sucrose, urea, or ethylenediaminetetraacetic acid (EDTA)) dissolved in de-ionized water. In the first method, preheating of the metal precursor?fuel solution was conducted on a hot plate at 300^oC or in a microwave furnace depending on the nature of the precursors. This heating technique provided fast vaporization of water followed by self?ignition of reactants. In the second method, the metal precursor?fuel solution was slowly evaporated at 50^oC and later heated in a muffle furnace up to 650^oC in air at a rate of 20 ^oC/min for nitrate decomposition in the presence of a carbonaceous fuel. While the former method resulted in amorphous oxide materials or multiple phases, the latter method led to the formation of a crystalline material in the form of nano-particles consisting mainly of a desired spinel ZnFe₂O₄ phase. Average crystallite sizes of synthesized ferrites calculated by the Scherrer's equation from X-ray diffraction (XRD) peaks were in the range of 14-32nm, which agreed with transmission electron microscope (TEM) observations. Scanning electron microscope (SEM) images of doped ferrites revealed that these nanocrystals are in the form of agglomerates. The specific surface area of the doped ferrites was found to be dependent on the synthesis method and a type of fuel used. Both synthesis methods and characterization of doped ferrite materials formed from metal nitrates and various fuels at different synthesis conditions will be presented.