Synthesis of Superparamagnetic Colloidal Nanochains as Magnetic-Responsive Bragg Reflectors

Superparamagnetic colloidal nanochains (CNCs) coated and linked by carbon were prepared by solvothermal decomposition of ferrocene at a temperature of 180−200 °C with a 0.20 T magnetic-field applied. It is demonstrated that CNCs with different intraparticle spaces (216, 186, and 173 nm) can be obtained by changing the reaction temperature. Under the induction of an external magnetic field (e.g., 0.10 T), the ethanol suspension of the three samples can diffract different wavelengths of visible light, displaying red, green, and blue color, respectively. The three samples did not show the dependence of the diffraction wavelength on the strength of induction magnetic field, which indicates that the superparamagnetic CNCs can be used as magnetic-responsive Bragg reflectors.