Rare earth metal compound in aqueous solvent, method for producing same, and method for producing ceramic powder using same

Abstract

A particulate subcomponent for a barium titanate dielectric is obtained from a sol in which a rare earth metal compound is dispersed in water. The rare earth metal compound includes a carboxylic acid having at least three carbonyl groups and at least one rare earth metal selected which can be Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and/or Lu in which the molar ratio (carbonyl group/rare earth metal) is in the range of 1.2 to 3. A method of making the sol and a method of using the sol to make a ceramic power is also described.

1 . A water-based rare earth metal compound sol comprising: a rare earth metal compound dispersed in water, wherein the rare earth metal compound comprises a carboxylic acid or a carboxylate which has at least three carbonyl groups and at least one rare earth metal selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and wherein the molar ratio of carbonyl groups to the rare earth metal is in the range of 1.2 to 3.  
     
     
         2 . The water-based rare earth metal compound sol according to  claim 1 , wherein the carboxylic acid or the carboxylate is citric acid or a citrate, respectively.  
     
     
         3 . A method for manufacturing a water-based rare earth metal compound sol, comprising: providing an acidic or an alkaline aqueous solution of at least one rare earth metal selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or a water-based dispersion containing one or more hydroxides of the aforementioned rare earth metal; and combining a carboxylic acid or a carboxylate which has at least three carbonyl groups with the solution or dispersion such that the molar ratio of carbonyl groups to the rare earth metal is in the range of 1.2 to 3.  
     
     
         4 . The method for manufacturing a water-based rare earth metal compound sol, according to  claim 3 , wherein the carboxylic acid or the carboxylate is citric acid or a citrate, respectively.  
     
     
         5 . A method for manufacturing a ceramic powder, comprising combining the water-based rare earth metal compound sol according to  claim 1  with the ceramic.  
     
     
         6 . The method for manufacturing a ceramic powder according to  claim 5 , wherein the carboxylic acid or the carboxylate is citric acid or a citrate  
     
     
         7 . The method for manufacturing a ceramic powder according to  claim 6 , wherein the sol is combined with a slurry of the ceramic.  
     
     
         8 . The method for manufacturing a ceramic powder according to  claim 7 , wherein the ceramic is barium titanate.  
     
     
         9 . The method for manufacturing a ceramic powder according to  claim 5 , wherein the sol is combined with a slurry of the ceramic.  
     
     
         10 . The method for manufacturing a ceramic powder according to  claim 9 , wherein the ceramic is barium titanate.  
     
     
         11 . The method for manufacturing a water-based rare earth metal compound sol according to  claim 4 , wherein a solution is combined with the carboxylic acid or carboxylate.  
     
     
         12 . The method for manufacturing a water-based rare earth metal compound sol according to  claim 4 , wherein a dispersion is combined with the carboxylic acid or carboxylate.  
     
     
         13 . The method for manufacturing a water-based rare earth metal compound sol according to  claim 3 , wherein a solution is combined with the carboxylic acid or carboxylate.  
     
     
         14 . The method for manufacturing a water-based rare earth metal compound sol according to  claim 3 , wherein a dispersion is combined with the carboxylic acid or carboxylate.  
     
     
         15 . The method for manufacturing a water-based rare earth metal compound sol according to  claim 3 , wherein a pH adjustment agent, water, or both are added to the combination.  
     
     
         16 . The method for manufacturing a water-based rare earth metal compound sol according to  claim 3 , further comprising preparing the acidic or alkaline aqueous solution.  
     
     
         17 . The water-based rare earth metal compound sol according to  claim 1 , wherein the carboxylic acid or the carboxylate is selected from the group consisting of triammonium citrate, citric acid and ethylenediaminetetraacetate.  
     
     
         18 . The water-based rare earth metal compound sol according to  claim 17 , wherein the rare each metal comprises Ho, Y or Dy.  
     
     
         19 . The water-based rare earth metal compound sol according to  claim 1 , wherein the rare each metal comprises Ho, Y or Dy.