A Comparison of Iron Oxides Photodeposited in Porous Vycor Glass and Tetramethoxysilane/Methanol/Water Xerogels

The iron oxides obtained by photolysis of Fe(CO)₅ physisorbed onto porous Vycor glass (PVG) are compared to those obtained in tetramethoxysilane/methanol/water xerogels. Mossbauer and X-ray absorption fine structure, extended, data indicate the formation of surface-bound, octahedrally coordinated Fe³⁺ species in both materials. Although photoimaging experiments show that iron oxide images of equivalent resolution can be deposited in both glasses, consolidation of the PVG samples, but not the xerogel samples, yields magnetically ordered materials exhibiting magnetic hyperfine fields of 370 and 425 kG, respectively. Formation of a magnetically ordered material depends on initial Fe(CO)₅ loading, and its occurrence in one glass, but not the other, is thought to reflect differences in the morphologies of the two materials.