Synthesis of Nanostructured Iron Oxide(III) Powders by Rapid Expansion of Supercritical Fluid Solutions

Abstract

ABSTRACTNanostructured a-Fe2O3 powders were generated by rapid expansion of supercritical fluid solutions (RESS, T=773 K, P=100 MPa) and by rapid thermal decomposition of precursors in solution ( RTDS, T=623 K, P=100 MPa) on lab RESS-setup from 0,040 M and 0,10 M aqueous solutions of Fe(NO3)3. The size of subcrystallites is about 22-29 nm. Comparison of reactivity of α-Fe2O3 powders in a model solid state reaction between a-Fe2O3 powders (generated by RESS from 0,040 M solution) and Li2CO3 (mole ratio 1:1) with literature data on a-Fe2O3 powders produced by other methods shows that its reactivity is markedly higher. A basic essence possibility of zinc ferrite ZnFe2O4 formation immediately at the stage of the rapid expansion (T=773K; P=100 MPa) of a supercritical aqueous solution of zinc and iron nitrates (molar ratio Zn:Fe=1:2; C=0. 1 M) was shown.