The use of organic (surfactants) to produce and stabilize ferrishpinel particles

Abstract

Usually, the formation of ultrafine ferrites with a certain particle size and morphology is carried out in the presence of surfactants by microemulsion methods; sol-gel polyol and matrix synthesis, as well as high-temperature decomposition of organometallic compounds. Most of these methods make it possible to regulate the microstructure of particles, but they are not acceptable for obtaining large volumes of dispersions due to the high cost and complexity of the synthesis procedure, high reaction temperatures, significant duration of the ferrite formation process itself, toxicity of reagents and related reaction products, which is a potential threat to the environment. Among the most common surfactants used in the synthesis of nanoscale ferrishpinel particles, citric acid (citrate) acid has been isolated, which is used to produce a citrate gel precursor. Other substances that contribute to the formation of colloidically stable ferrispinel particles suitable for use in biological systems are polyethylene glycol (PEG) or polyvinyl alcohol (PVA). Synthesis of cobalt-containing ferrispinel particles in a polyester polymer precursor obtained by simultaneous use of citrate acid and ethylene glycol. In a separate row are the higher carboxylic acids, among which oleic acid is most often used in the synthesis of oxide and ferrite particles. The synthesis of monodisperse nanocrystals is also carried out during the chemical decomposition of organometallic precursors, for example, in the presence of octyl ether.