Liquid crystal templated deposition method

Abstract

When depositing a metal or a compound of the metal from a liquid crystal phase comprising a metal compound, e.g. a metal salt, by electrochemical means, high concentrations of the salt may be employed by using an ionic surfactant in place of the commonly used non-ionic surfactant.

1 . A process which comprises: forming a mixture comprising a metal compound from which the metal or a compound of the metal may be deposited, a solvent and a surfactant in amounts sufficient to form a liquid crystal phase in the mixture; and electrochemically depositing the metal or a compound of the metal from the metal compound, characterised in that the surfactant is an ionic surfactant and the metal compound is present in the aqueous component of the liquid crystal phase-containing mixture at a concentration which, in a comparative mixture identical to the liquid crystal phase-containing mixture except that the ionic surfactant is replaced by a mixture of compounds of general formula CH 3 —(CH 2 ) 15 —(CH 2 CH 2 O) y —OH, where y is a number and the abundance of the compound having that value of y is approximately that shown in the following Table, 
     
       
         
               
               
               
             
                   
                   
               
                   
                   
                 % Abundance 
               
                   
                   
                 in Surfactant 
               
                   
                 y 
                 Component 
               
                   
                   
               
                   
               
               
               
               
             
                   
                 3 
                 1.7 
               
                   
                 4 
                 2.8 
               
                   
                 5 
                 4.0 
               
                   
                 6 
                 5.6 
               
                   
                 7 
                 7.3 
               
                   
                 8 
                 9.4 
               
                   
                 9 
                 10.8 
               
                   
                 10 
                 11.1 
               
                   
                 11 
                 11.1 
               
                   
                 12 
                 10.8 
               
                   
                 13 
                 8.5 
               
                   
                 14 
                 6.4 
               
                   
                 15 
                 4.9 
               
                   
                 16 
                 3.4 
               
                   
                 17 
                 2.2 
               
                   
                   
               
           
              
              
              
              
              
             
             
              
             
          
           
              
              
              
              
              
              
              
              
              
              
              
              
              
              
              
              
             
          
         
       
     
     would cause the liquid crystal phase to be unstable or produce a deposit with a cathodic charge density less than half the value of that obtained using the ionic surfactant, with the same deposition charge density. 
   
   
       2 . A process which comprises: forming a mixture comprising a metal compound from which the metal or a compound of the metal may be deposited, a solvent and a surfactant in amounts sufficient to form a liquid crystal phase in the mixture; and electrochemically depositing the metal or a compound of the metal from the metal compound, characterised in that the surfactant is an ionic surfactant and the metal compound is present in the aqueous component of the liquid crystal phase-containing mixture at a concentration of at least 0.4 M. 
   
   
       3 . A process according to  claim 1 , in which the metal is selected from the group consisting of nickel, platinum, cobalt, iron, tin, lead, selenium, manganese, chromium, copper, zinc, niobium, molybdenum, titanium, palladium, gold, silver, cadmium, and mercury, or a mixture or alloy of any two or more thereof. 
   
   
       4 . A process according to  claim 3 , in which the metal is nickel, cobalt, zinc, iron, tin, copper, lead, selenium, or cadmium, or a mixture or alloy of any two or more thereof. 
   
   
       5 . A process according to  claim 3 , in which the metal is nickel or cobalt or a mixture or alloy thereof. 
   
   
       6 . A process according to  claim 1 , in which the compound of the metal is an oxide or hydroxide or a mixture thereof. 
   
   
       7 . A process according to  claim 1 , in which the concentration of said metal compound is at least 0.4 M. 
   
   
       8 . A process according to  claim 7 , in which the concentration of said metal compound is from 0.4 M to 4 M. 
   
   
       9 . A process according to  claim 1 , in which the surfactant has an ionic group attached, directly or indirectly, to one or more hydrocarbon chains having at least 8 carbon atoms. 
   
   
       10 . A process according to  claim 9 , in which the surfactant is a compound of formula NR 1 R 2 R 3  or N − R 1 R 2 R 3 R 4 X − , where at least one of R 1 , R 2  and R 3  or R 1 , R 2 , R 3  and R 4  represents a hydrocarbon group having at least 8 carbon atoms, and X −  represents an anion. 
   
   
       11 . A process according to  claim 8 , in which the surfactant is a salt containing long chain fatty acid or hydrocarbon residues, said residues each having at least 8 carbon atoms. 
   
   
       12 . A process according to  claim 1 , in which the surfactant is cetyltrimethylammonium chloride, cetyltrimethylammionium bromide, sodium dodecyl sulphate, hexadecyl amine, dodecyltrimethylammonium chloride or dioctyl sodium sulphosuccinate. 
   
   
       13 . A process according to  claim 12 , in which the surfactant is cetyltrimethylammonium bromide. 
   
   
       14 . A process according to  claim 2  in which the metal is selected from the group consisting of nickel, platinum, cobalt, iron, tin, lead, selenium, manganese, chromium, copper, zinc, niobium, molybdenum, titanium, palladium, gold, silver, cadmium, and mercury, or a mixture or alloy of any two or more thereof. 
   
   
       15 . A process according to  claim 14 , in which the metal is nickel, cobalt, zinc, iron, tin, copper, lead, selenium, or cadmium, or a mixture or alloy of any two or more thereof. 
   
   
       16 . A process according to  claim 14 , in which the metal is nickel or cobalt or a mixture or alloy thereof. 
   
   
       17 . A process according to  claim 14 , in which the compound of the metal is an oxide or hydroxide or a mixture thereof. 
   
   
       18 . A process according to  claim 14 , in which the concentration of said metal compound is at least 0.4 M. 
   
   
       19 . A process according to  claim 14 , in which the surfactant has an ionic group attached, directly or indirectly, to one or more hydrocarbon chains having at least 8 carbon atoms. 
   
   
       20 . A process according to  claim 14 , in which the surfactant is a salt containing long chain fatty acid or hydrocarbon residues, said residues each having at least 8 carbon atoms.