Abstract
Two methods for the preparation of magnetic iron oxide starting from FeSO 4 · 7H 2O are described. The traditional method involves preparation of Fe(OH) 2 seed material, conversion of the seed to acicular γ-FeOOH crystals, dehydration of the crystals to α-Fe 2O 3, hydrogen reduction of Fe 2O 3 to magnetite, and finally reoxidation of magnetite particles to γ-Fe 2O 3. Magnetic iron oxide particles thus obtained, after a total processing time of about 25 h, have a coercivity between 330 and 380 Oe. The other method, known as the direct method, involves fewer steps, a shorter overall processing time, and yields magnetic iron oxide having an equivalent or higher coercivity value. A sample from the seed preparation solution is recrystallized at 250 °C, yielding a product, γ-Fe 2O 3, which has a coercivity value of 320 Oe. In another procedure the seed is prepared in the presence of H 2O 2 as the oxidizing agent and recrystallized at 300 °C for 2 h to yield γ-Fe 2O 3 having 390 Oe coercivity.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
