Synthesis and characterization of hybrid silica aerogel and its magnetic nanocomposite material

Aerogels are porous inorganic polymers having high porosity, low density, highspecific surface areas, low refraction index in addition to very little thermal conductivity [۱]. Dueto their exceptional properties, they have found numerous advanced applications [۲]. They aretypically synthesized via common sol–gel chemistry and subsequent supercritical dryingprocedure in order to prevent destroying the porous structure by capillary stress [۳]. The sol–gelsynthesis includes hydrolysis catalyzed by acid or base and then silicon alkoxides condensation.Silica aerogels are achieved by atmospheric pressure drying technique in which both of thenetwork strengthening as well as surface modification happen before the drying stage [۴,۵].Herein, hybrid silica aerogel (HSA) nanoparticles were synthesized by sol-gel method anddrying at ambient pressure. Also, a magnetic nanocomposite of HSA with Fe۳O۴ nanoparticles(HSA-Fe۳O۴) was prepared. The morphology, structure and magnetic properties of the HSA aswell as its nanocomposite were analyzed by SEM, XRD, VSM and ATR-FTIR techniques. Thesaturation magnetization (Ms) values for the Fe۳O۴ NPs, and HSA-Fe۳O۴ nanocomposite filmwere ۶۹.۹۳, and ۱۹.۰۴ emu g–۱, respectively. The XRD pattern of the Fe۳O۴ NPs exhibited thestandard peaks at ۲θ values near ۳۰, ۳۵, ۴۳, ۵۳, ۵۷ and ۶۳° related to the crystallographic planes(۲۲۰), (۳۱۱), (۴۰۰), (۴۲۲), (۵۱۱) and (۴۴۰) matched the JCPDS card No. ۷۵-۱۰۶۹. The HSAillustrated a broad peak centered at around ۱۹.۹۱° signifying its amorphous nature. The XRDpattern of the HSA-Fe۳O۴ NPs was similar to that of the HSA but the Fe۳O۴ NPs peaks wereobserved due to the presence of higher amount (۷۰ w/w%) of HSA in the HSA-Fe۳O۴ NPscomposite.