کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1801530 | 1024571 | 2010 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Magnetic properties of iron loaded MCM-48 molecular sieves Magnetic properties of iron loaded MCM-48 molecular sieves](/preview/png/1801530.png)
Mesoporous molecular sieves of MCM-48 type were loaded with iron by the wet impregnation method, using Fe(III) nitrate or Fe(II) sulfate aqueous solutions as Fe sources, to obtain a magnetic porous composite. The iron loaded materials were characterized by XRD, N2 adsorption and DRUV-vis and compared with the Si-MCM-48 host. Their magnetic properties were studied by measuring the hysteresis loops up to 1.5 T at different temperatures (5–300 K) and by magnetization vs. temperature curves following the conventional zero field cooling (ZFC) and field cooling (FC) protocols. Materials with high structure regularity and surface area are obtained, which exhibit a mixed paramagnetic and superparamagnetic behavior, arising in isolated iron ions inserted in the host framework, and in small iron oxide clusters or nanoparticles forming inside the pores, respectively. Larger hematite particles (8–13 nm) grown on the external surface provide a quite small ferromagnetic contribution to the hysteresis loop.
Journal: Journal of Magnetism and Magnetic Materials - Volume 322, Issue 21, November 2010, Pages 3438–3442