Nanoparticle, method of producing nanoparticle and magnetic recording medium

Abstract

A method of producing a nanoparticle, the method comprising: a reducing step of adding an reverse micelle solution (II) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous metal salt solution to an reverse micelle solution (I) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous reducing agent solution, to carry out a reducing reaction; and a maturing step of raising the temperature of the reduced mixture to mature the reduced mixture is provided. A method of producing a plural type alloy nanoparticle, the method comprising producing a nanoparticle made of a plural type alloy through a reducing step of mixing one or more reverse micelle solutions (I) containing a metal salt with an reverse micelle solution (II) containing a reducing agent to carry out reducing treatment and a maturing step of carrying out maturing treatment is also provided.

1 - 12 . (canceled)  
     
     
         13 . A nanoparticle produced by a method comprising a reducing step of adding an reverse micelle solution (II) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous metal salt solution to an reverse micelle solution (I) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous reducing agent solution, to carry out a reducing reaction; and 
 a maturing step of raising the temperature of the reduced mixture of micelle solutions (I) and (II) to mature the reduced mixture after the reducing reaction is completed, wherein    the ratio (water/surfactant) by mass of water to the surfactant in each of the reverse micelle solutions (I) and (II) is 20 or less;    the reducing reaction temperature is constant in a range from −5 to 30° C.; and    the maturing temperature is higher than the reducing reaction temperature and is constant in a range from 30 to 90° C., and the maturing time is 5 to 180 minutes.    
     
     
         14 . A magnetic recording medium comprising at least a magnetic layer formed on a support, wherein 
 the magnetic layer is formed by applying a dispersion solution in which a nanoparticle is dispersed to the support and an annealing treatment is performed;    the nanoparticle being produced by a method comprising a reducing step of adding an reverse micelle solution (II) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous metal salt solution to an reverse micelle solution (I) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous reducing agent solution, to carry out a reducing reaction; and    a maturing step of raising the temperature of the reduced mixture of micelle solutions (I) and (II) to mature the reduced mixture, and    the ratio (water/surfactant) by mass of water to the surfactant in each of the reverse micelle solutions (I) and (II) is 20 or less;    the reducing reaction temperature is constant in a range from −5 to 30° C.; and    the maturing temperature is higher than the reducing reaction temperature and is constant in a range from 30 to 90° C., and the maturing time is 5 to 180 minutes.    
     
     
         15 - 18 . (canceled)  
     
     
         19 . A nanoparticle that is made of a plural type alloy through a reducing step of mixing one or more reverse micelle solutions (I) containing a metal salt with an reverse micelle solution (II) containing a reducing agent to carry out reducing treatment and a maturing step of carrying out maturing treatment after the reducing treatment, wherein 
 at least two metals constituting the plural type alloy are selected from the VIb group and VIII group in the periodic table; and    at least one metal constituting the plural type alloy is selected from the Ib group, IIIa group, IVa group and Va group and the content of the selected metals is 1 to 30 at. % in all of the plural type alloy.    
     
     
         20 . The nanoparticle of  claim 19 , wherein the coefficient of variation in the particle diameter distribution of the nanoparticles.  
     
     
         21 . A magnetic recording medium comprising at least a magnetic layer formed on a support, wherein; 
 the magnetic layer is formed by applying a dispersion solution prepared by dispersing nanoparticles and by carrying out annealing treatment, wherein the nanoparticles are made of a plural type alloy through a reducing step of mixing one or more reverse micelle solutions (I) containing a metal salt with an reverse micelle solution (II) containing a reducing agent to carry out reducing treatment and a maturing step of carrying out maturing treatment after the reducing treatment, wherein    at least two metals constituting the plural type alloy are selected from the VIb group and VIII group in the periodic table; and    at least one metal constituting the plural type alloy is selected from the Ib group, IIIa group, IVa group and Va group and the content of the selected metals is 1 to 30 at. % in all of the plural type alloy.    
     
     
         22 . The magnetic recording medium of  claim 21 , wherein the coercive force of the nanoparticle is 95.5 to 1193.8 KA/m (1200 to 15000 Oe).