Laser Synthesis of Magnetic Nanoparticles in Liquids and Application in the Fabrication of Polymer–Nanoparticle Composites

Abstract

The method of synthesis of nanoparticles in solution by laser ablation of a bulk target material immersed in a liquid does not require the use of any reducible chemical precursors or colloidal stabilizing agents. The resulting colloids are ultrapure, and in certain cases, the synthesized nanoparticles are surface-ligand-free (have “bare” surfaces). Furthermore, laser irradiation of micro/nanomaterials suspended in a liquid can lead to the synthesis of nanoparticles in solution with unique physicochemical properties. Interest in the application of the method for the synthesis of magnetic nanoparticles usually originates from the following facts: (i) Magnetic oxide or carbide nanoparticles can be directly synthesized by laser ablating the corresponding elemental target material in the appropriate liquid, (ii) magnetoplasmonic bimetallic alloy nanoparticles (e.g., FeAu), even composed of elements that are immiscible at any temperature in the solid or liquid phase (e.g., FeAg, CoAg), can be synthesized by ablating nonalloyed bimetallic targets, (iii) under the application of an external magnetic field, nanoparticle chains and strands can be fabricated that are characterized by a high packing density of the nanoparticles that together with their “bare” surfaces result in the strands having both a high aspect ratio and electrical conductivity, (iv) magnetic nanostructures that consist of nanoparticles and nanomaterials with different morphologies or properties can be fabricated, and (v) nanoparticles of intrinsically nonmagnetic oxides exhibiting the so-called d0 ferromagnetism can be synthesized. By using laser-synthesized-in-liquid magnetic nanoparticles in the fabrication of polymer–nanoparticle composites (magnetic nanocomposites), the presence of any chemical reaction byproducts in the nanocomposite is avoided. The nanoparticles form direct chemical bonds with the polymer matrix. Nanoparticle strands formed in the nanocomposite provide it with a high electrical conductivity while preserving its optical transparency. This Review is focused on the synthesis of magnetic nanoparticles in solution by laser ablation of a bulk target material immersed in a liquid or laser irradiation of micro/nanoparticles or micro/nanomaterials suspended in a liquid and the fabrication of magnetic nanocomposites using these nanoparticles.