Method for producing nanoparticles for magnetic fluids by electron-beam evaporation and condensation in vacuum, a magnetic fluid producing method and magnetic fluid produced according to said method

A method of producing a magnetic fluid containing nanoparticles of a magnetic material of a specified size, comprising the steps of:

• evaporating an initial solid inorganic magnetic material selected from the group comprising metals, alloys or oxides thereof;
• evaporating a carrier made of a solid liquid-soluble material simultaneously with said evaporation of the initial solid material by electron-beam heating, the carrier concentration being in the range of from 99 to 70% in a total mixed vapor of the initial solid inorganic magnetic material and the solid liquid-soluble material;
• using a solid liquid-soluble inorganic material selected from a group containing salts of alkali and alkali-earth metals and mixtures thereof as the solid liquid-soluble material of the carrier fixing magnetic nanoparticles of the magnetic material;
• and
• depositing the mixed vapor on a substrate, the step of depositing the vapor on the substrate including:
• fixing the magnetic nanoparticles of the solid inorganic magnetic material during condensation of the mixed vapor on a cooled substrate by solidifying the solid liquid-soluble material on the substrate;
• adjusting a nanoparticle size by presetting and maintaining the temperature at a specified value below the melting point of the solid liquid-soluble material during deposition of the mixed vapor;
• obtaining a condensate of the magnetic nanoparticles having a specified size, fixed in the carrier;
• extracting the magnetic nanoparticles from the condensate by diluting the condensate in at least one type of liquid;
• and
• stabilizing the magnetic nanoparticles in a fluid by a surface-active agent dissolved in said fluid thereby attaining the magnetic fluid containing the magnetic nanoparticles.