Surface modified nickel nanoparticle, and conductive paste and multi-layer capacitor comprising the same

Abstract

A method for surface treatment of nickel nanoparticles using an organic solution, including dispersing nickel nanoparticles in a reductive organic solvent to obtain homogeneity; heating the dispersion of nickel nanoparticles; and separating the solution after treatment, washing and drying. Nickel nanoparticles treated by this method are preferably substantially free of impurities remaining on particle surfaces and thus have smooth surfaces and increased tap density, and the use thereof enables efficient production of a multi-layer ceramic capacitor.

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       5 . The surface modified nickel nanoparticle according to  claim 10 , wherein the reductive organic solvent is propanediol, butanediol, pentanediol, octanol, ethyleneglycol, propyleneglycol, diethyleneglycol, dipropyleneglycol, hexyleneglycol, or butyleneglycol. 
   
   
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       7 . The surface modified nickel nanoparticle according to  claim 10 , wherein said basic solution is added to said dispersion of nickel nanoparticles in an amount between 0.2 and 1% by weight relative to said reductive organic solvent. 
   
   
       8 . The surface modified nickel nanoparticle according to  claim 10 , wherein said basic solution is added to said dispersion of nickel nanoparticles in an amount of more than 0.1% by weight, relative to said reductive organic solvent. 
   
   
       9 . (canceled) 
   
   
       10 . A surface modified nickel nanoparticle formed through the surface treatment of nickel nanoparticles comprising:
 dispersing nickel nanoparticles formed by a wet chemical process having a diameter of 100 nm to 1,000 nm and impurities of Ni(OH) 2  and/or Ni 2 O 3  adhering to their surfaces in a reductive organic solvent which is a primary or secondary alcohol containing 3 to 8 carbon atoms or a glycol containing 2 to 6 carbon atoms and a solution of a base selected from the group consisting of NaOH and KOH to obtain a dispersion wherein said nanoparticles are present in the dispersion in a concentration of 5 to 10% by weight based on the weight of said reductive organic solvent;   heating the resulting dispersion at a temperature 10 to 50° C. lower than the boiling temperature of said reductive organic solvent to provide surface modification wherein said Ni(OH) 2  and/or NI 2 O 3  adhering to the surfaces of said nickel nanoparticles is reduced to nickel metal so as to increase a surface homogeneity of the nickel nanoparticles;   separating the resulting nickel nanoparticles from the dispersion; and   washing and drying the resulting modified nickel nanoparticles to provide a nanoparticle product having increased surface homogeneity and an increased tap density when compared to that of the starting material.   
   
   
       11 . (canceled) 
   
   
       12 . The surface modified nickel nanoparticle according to  claim 10 , wherein nanoparticle is substantially free of surface impurities. 
   
   
       13 . A conductive paste comprising surface modified nickel nanoparticles according to  claim 10 . 
   
   
       14 . The conductive paste according to  claim 13 , further comprising an organic binder and an organic solvent. 
   
   
       15 . The conductive paste according to  claim 14 , wherein the organic binder is ethylcellulose. 
   
   
       16 . The conductive paste according to  claim 14 , wherein the organic solvent comprises terpineol, dihydroxy terpineol, 1-octanol, or kerosene. 
   
   
       17 . The conductive paste according to  claim 14 , wherein the surface modified nickel nanoparticles are present in a concentration of 40 to 60% by weight, the organic binder is present in a concentration of 0.8 to 4% by weight, and the organic solvent is present in a concentration of 40 to 60% by weight. 
   
   
       18 . The conductive paste according to  claim 13 , further comprising a plasticizer, an anti-thickening agent, and a dispersant. 
   
   
       19 . A multi-layer ceramic capacitor comprising internal electrodes comprised of the surface modified nickel nanoparticles of  claim 10 . 
   
   
       20 . The multi-layer ceramic capacitor according to  claim 19 , wherein the surface modified nickel nanoparticles are substantially free of surface impurities. 
   
   
       21 . The surface modified nickel nanoparticle according to  claim 10 , wherein said basic solution is NaOH. 
   
   
       22 . The surface modified nickel nanoparticle according to  claim 10 , wherein said basic solution is KOH.