Evidence for superparamagnetism within a molecular sieve: Magnetic and Mössbauer effect studies

A novel method for dispersing iron inside a silicate matrix, more specifically molecular sieve 13X, has been developed. This has obvious advantages over iron dispersions on external surfaces, as in catalysts, thin films, etc. The transition from paramagnetism to superparamagnetism to antiferromagnetism has been studied in this zeolite system (molecular sieve 13X) into which Fe³⁺has been introduced. Both Fe(CO)5and FeCl3have been used to obtain Fe2O3under certain conditions as described. Magnetic susceptibility, Mössbauer spectroscopy, X-ray diffraction, and electron microscopy have been used to elucidate the resulting products.