Synthesis, characterization and magnetic properties of ε-Fe2O3 nanoparticles prepared by sol-gel method

Nanoparticles of epsilon-Fe2O3 in an amorphous silica matrix were prepared by the sol-gel method without using a precursor. X-ray diffraction patterns reflect a completely amorphous state for the samples even after heat-treated up to 600 degrees C, while at higher temperatures the formation of crystalline iron oxide phases was observed. Transmission electron microscopy analysis showed a wide size distribution of nanoparticles from 3(+/- 0.5) to 46(+/- 0.8) nm. The occurrence of epsilon-Fe2O3 particles depends on several factors like annealing temperature, particle size and iron concentration in initial chemicals. Based on the Fe-57 Mossbauer spectra, three octahedral and one tetrahedral iron site were identified for epsilon-phase. The optimized conditions for the preparation of epsilon-Fe2O3 rich sample were confirmed and similar to 90% of the epsilon-Fe2O3 phase was obtained with the particle size of 15(+/- 0.6) nm. The high coercivity of similar to 1.18 T at room temperature was confirmed for our nanoparticle system.

Automated summary

In this study, nanoparticles of ε-Fe2O3 in an amorphous silica matrix were prepared using the sol-gel method, showing wide size distribution and dependence on various factors. X-ray diffraction patterns and transmission electron microscopy analysis were used to characterize the samples, revealing the formation of crystalline iron oxide phases at higher temperatures and the presence of octahedral and tetrahedral iron sites in the ε-phase. The optimized conditions for preparation of ε-Fe2O3 rich sample were confirmed, achieving around 90% of the ε-Fe2O3 phase with a particle size of 15 nm and demonstrating high coercivity of approximately 1.18 T at room temperature in the nanoparticle system.