Deposition of magnetite on AgI-silica core-shell particles by homogeneous precipitation method

Abstract

A method for magnetite-deposition on Agl-SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> core- shell (Agl/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) particles is proposed. A colloid solution of 1.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> M Agl nanoparticles was prepared mixing silver perchlorate at 1.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> M and potassium iodide at 2.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> M at 5°C, and then adding 3-mercaptopropyltrimethoxysilane at 4.5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> M at 20°C. Agl/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> particles with an average size of 42.7±10.3 nm and a Agl core size of 23.5±5.8 nm were prepared using a Stober method at 20°C in water/ethanol solution with 8.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> M tetraethylorthosilicate and 1.1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> M NaOH in the presence of 1.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> M Agl nanoparticles. Preparation of magnetite nanoparticle colloid solution was performed with a homogeneous precipitation method using 5.0 M urea aqueous solution and 1.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> M iron chloride aqueous solution with Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> /Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> molecular ratios of 1/0, 2/1, 1/2 and 0/1 in (50/50) (v/v) water/1-propanol solution at 80°C. Magnetite that revealed ferromagnetic property were produced using the ratios of 1/0, 2/1 and 1/2. Magnetite-deposition on the Agl/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> particles was performed preparing the magnetite by the homogeneous precipitation method using 1.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> M iron chloride and 5.0 M urea in the presence of the Agl/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> particles ([Agl] = 2.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> M). Tiny magnetite nanoparticles were deposited on the Agl/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> particle surface. The magnetite-deposited Agl/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> particles were ferromagnetic, and were drawn close to magnet. These results confirmed that the homogeneous precipitation method was suitable to magnetite-deposition.