Thermally stimulated iron oxide transformations and magnetic behaviour of cerium dioxide/iron oxide reactive sorbents

Abstract

The present paper is devoted to detailed study of the magnetically separable sorbents based on a ceriumdioxide/ iron oxide composite annealed at temperatures Ta=773 K, 873 K, and 973 K. The X-ray diffraction and high resolution transmission electronmicroscopy are used to determine the phase composition andmicrostructuremorphology. Mössbauer spectroscopy at room (300 K) and low (5 K) temperatures has contributed to more exact identification of iron oxides and their transformations Fe3O4 → γ-Fe2O3 (ε-Fe2O3) → α-Fe2O3 in dependence on calcination temperature. Different iron oxide phase compositions and grain size distributions influence the magnetic characteristics determined from the room- and low-temperature hysteresis loop measurements. The results are supported by zero-field-cooled and field-cooledmagnetizationmeasurements allowing a quantitative estimation of the grain size distribution and its effect on the iron oxide transformations.