Abstract
Effects of calcination temperatures varying from 400 to 1000°C on structural and magnetic properties of nanocomposites formed by Co-ferrite dispersed in the sol-gel silica matrix using tetrakis(2-hydroxyethyl) orthosilicate (THEOS) as water-soluble silica precursor have been investigated. Studies carried out using XRD, FT-IR, TEM, STA (TG-DTG-DTA) and VSM techniques. Results indicated that magnetic properties of samples such as superparamagnetism and ferromagnetism showed great dependence on the variation of the crystallinity and particle size caused by the calcination temperature. The crystallization, saturation magnetization Ms and remenant magnetization Mr increased as the calcination temperature increased. But the variation of coercivity Hc was not in accordance with that of Ms and Mr, indicating that Hc is not determined only by the crystallinity and size of CoFe2O4 nanoparticles. TEM images showed spherical nanoparticles dispersed in the silica network with sizes of 10-30 nm. Results showed that the well-established silica network provided nucleation locations for CoFe2O4 nanoparticles to confinement the coarsening and aggregation of nanoparticles. THEOS as silica matrix network provides an ideal nucleation environment to disperse CoFe2O4 nanoparticles and thus to confine them to aggregate and coarsen. By using THEOS as water-soluble silica precursor over the currently used TEOS and TMOS, the organic solvents are not needed owing to the complete solubility of THEOS in water. Synthesized nanocomposites with adjustable particle sizes and controllable magnetic properties make the applicability of Co-ferrite even more versatile.
Highlights
Effects of calcination temperature on structural and magnetic properties of cobalt ferrite nanocomposites in silica matrix prepared by sol-gel method using tetrakis(2-hydroxyethyl) orthosilicate (THEOS) as silica precursor have been reported aiming at tuning the magnetic properties of CoFe2O4 nanoparticles dispersed in a sol gel silica matrix and greatly expanding the range of applications by adjusting the calcination temperature
X-ray diffraction (XRD) analysis The XRD patterns of the samples calcined at different temperatures varying from 400 to 1000°C were shown in Figure 1 to investigate the influence of the calcination temperature on the structure
Our results showed that with increasing calcination temperature, the intensity of peaks increases and the
Summary
Based on the above technological challenge and scientific importance, researches such as ceramic method [13], sol-gel [14], co-precipitation [15], solvent evaporation [16], hydrothermal [17], combustion [18], microemulsion [19] and citrate methods [20] have been made into various synthesis routes of nanocrystalline ferrites. To reduce the unwanted crystallite coarsening and particles aggregation, attempts have been made to synthesize nanocomposites by embedding ferrite nanoparticles in a suitable matrix [23] Different matrixes such as resins [24], polymer films [25] and silica glasses [26,27] have been studied. Effects of calcination temperature on structural and magnetic properties of cobalt ferrite nanocomposites in silica matrix prepared by sol-gel method using tetrakis(2-hydroxyethyl) orthosilicate (THEOS) as silica precursor have been reported aiming at tuning the magnetic properties of CoFe2O4 nanoparticles dispersed in a sol gel silica matrix and greatly expanding the range of applications by adjusting the calcination temperature. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
