Assembly of Centimeter Long Silica Coated FePt Colloid Crystals with Tailored Interstices by Magnetic Crystallization

A new bottom-up approach using magnetic crystallization for the synthesis of centimeter long silica coated magnetic FePt colloidal crystals is for the first time revealed. HRTEM, SAX, BET, and VSM indicate that hcp packed colloidal crystals are composed of three-dimensional regular arrays of superparamagnetic FePt nanoparticle encapsulated in a protective hydrophilic silica shell with controllable thickness depending on gelation times which create adjustable internal interstices.