Predicting a major role of surface spins in the magnetic properties of ferrite nanoparticles

✍ Scribed by I. M. Obaidat; V. Mohite; B. Issa; N. Tit; Y. Haik

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 152 KB
• Volume: 44
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.200900022

✦ Synopsis

Room-temperature magnetization hysterisis measurements were conducted on Mn 0.5 Zn 0.5 Gd x Fe (2-x) O 4 ferrite nanoparticles, with x = 0, 0.5, 1.0, 1.5. The structure of this ferrite is normal spinel where the added of Gd 3+ ions occupied the octahedral sites and replaces Fe 3+ ions. The saturation magnetization was found to increase with the initial addition of the Gd 3+ ions followed by a sharp decrease with further addition of Gd 3+ ions. The Curie temperature was found to increase up to Gd 3+ concentration of x = 1.0, and then decreases at x = 1.5. These results were attributed to the surface spins. Because the size of Gd 3+ ions is larger than that of Fe 3+ ions, the substitution of Fe 3+ ions with the Gd 3+ ions results in surface disorder which results in surface spins. A core-shell magnetization model was introduced where several factors were combined to explain our results.