Inorganic acicular bodies and method for producing the same

Abstract

Acicular bodies of a metal compound are produced by slowly precipitating an organic salt of the metal from a solution of an ester of a dicarboxylic acid having 1-5 carbon atoms and firing the precipitate in an oxidizing atmosphere. These acicular bodies have a cross-sectional dimension less than about 20 μm and are useful for providing reinforcement of a larger ceramic body. Acicular bodies of rare-earth metal oxides also are useful in reinforcing x-ray scintillator bodies without diminishing their luminescent capacity.

1 - 6 . (canceled)  
     
     
         7 . A method for producing acicular bodies of at least one inorganic compound of a metal comprising the steps of: 
 preparing a solution of a precursor of said inorganic compound of said metal to obtain a first solution;    preparing a solution of an ester of a dicarboxylic acid to obtain a second solution;    adding said first solution in increments into said second solution to form a mixed solution and to obtain an acicular-shaped precipitate of an organic salt of said metal from said mixed solution;    separating said precipitate from said mixed solution;    drying said separated precipitate; and    firing said dried precipitate in an oxidizing atmosphere at a temperature for a time sufficient to convert said organic salt of said metal to acicular bodies of said inorganic compound of said metal;    wherein said metal is selected from the group consisting of Groups IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIA, VIIB, VIIIA of the Periodic Table, rare earth metals, and mixtures thereof.    
     
     
         8 . The method according to  claim 7 , wherein said at least one compound of said metal is an oxide of said metal.  
     
     
         9 . The method according to  claim 7 , wherein said precursor of said inorganic compound of said metal is soluble in water.  
     
     
         10 . The method according to  claim 7 , wherein said first solution is an acidic solution comprising an acid selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, citric acid, acetic acid, and mixtures thereof.  
     
     
         11 . The method according to  claim 7 , wherein said dicarboxylic acid is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, and mixtures thereof.  
     
     
         12 . The method according to  claim 11 , wherein said ester is selected from the group consisting of methyl, ethyl, propyl, dimethyl, diethyl, dipropyl esters, and mixtures thereof.  
     
     
         13 . The method according to  claim 7 , wherein said ester is selected from the group consisting of dimethyl oxalate, diethyl oxalate, and mixtures thereof.  
     
     
         14 . The method according to  claim 7 , wherein said inorganic compound of said metal is an oxide of said metal.  
     
     
         15 . The method according to  claim 7 , wherein said drying is carried out above a boiling point of a liquid of said mixed solution for a time sufficient substantially to remove a liquid from said precipitate.  
     
     
         16 . The method according to  claim 7 , wherein said firing is carried out at a temperature from about 400° C. to about 1400° C.  
     
     
         17 . The method according to  claim 7 , wherein said firing is carried out for about 4 hours.  
     
     
         18 . The method according to  claim 7 , wherein said oxidizing atmosphere is selected from the group consisting of air, oxygen, carbon dioxide, mixtures of oxygen and at least one inert gas, and mixtures thereof.  
     
     
         19 . A method for producing acicular bodies of at least one inorganic compound of a metal comprising the steps of: 
 preparing a solution of a precursor of said inorganic compound of said metal to obtain a first solution;    preparing a solution of an ester of a dicarboxylic acid to obtain a second solution;    adding said first solution in increments into said second solution to form a mixed solution and to obtain an acicular-shaped precipitate of an organic salt of said metal from said mixed solution;    separating said precipitate from said mixed solution;    drying said separated precipitate; and    firing said dried precipitate in an oxidizing atmosphere at a temperature for a time sufficient to convert said organic salt of said metal to acicular bodies of said inorganic compound of said metal;    wherein said metal is selected from the group consisting of Groups IIA, IIIA, IIIB of the Periodic Table, rare earth metals, and mixtures thereof.    
     
     
         20 . A method for producing acicular bodies of at least one inorganic compound of a metal comprising the steps of: 
 preparing a solution of a precursor of said inorganic compound of said metal to obtain a first solution;    preparing a solution of an ester of a dicarboxylic acid to obtain a second solution;    adding said first solution in increments into said second solution to form a mixed solution and to obtain an acicular-shaped precipitate of an organic salt of said metal from said mixed solution;    separating said precipitate from said mixed solution;    drying said separated precipitate; and    firing said dried precipitate in an oxidizing atmosphere at a temperature for a time sufficient to convert said organic salt of said metal to acicular bodies of said inorganic compound of said metal;    wherein said metal is selected from the group consisting of scandium, yttrium, lanthanum, aluminum, gallium, indium, thallium, cesium, praseodymium, neodymium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and mixtures thereof.    
     
     
         21 . A composite ceramic body comprising a ceramic matrix and acicular bodies of at least one inorganic compound of a metal selected from the group consisting of Groups IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA, VIB, VIA, VIIB, VIIIA of the Periodic Table, rare earth metals, and mixtures thereof; said acicular bodies being embedded in said ceramic matrix.  
     
     
         22 . A composite ceramic body comprising a ceramic matrix and acicular bodies of at least one inorganic compound of a metal selected from the group consisting of Groups IIA, IIIA, IIIB, IVA of the Periodic Table, rare earth metals, and mixtures thereof; said acicular bodies being embedded in said ceramic matrix.  
     
     
         23 . A composite ceramic body comprising a ceramic matrix and acicular bodies of at least one inorganic compound of a metal selected from the group consisting of scandium, yttrium, lanthanum, aluminum, gallium, indium, thallium, cesium, praseodymium, neodymium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and mixtures thereof; said acicular bodies being embedded in said ceramic matrix.  
     
     
         24 . The composite ceramic body according to  claim 23 , wherein said ceramic matrix and said acicular bodies have a same composition.  
     
     
         25 . The composite ceramic body according to  claim 24 , wherein said composite ceramic body comprises a scintillator of a computed tomography x-ray system.  
     
     
         26 . A composite ceramic body comprising a polycrystalline alumina matrix and acicular bodies of alumina embedded therein.  
     
     
         27 . A composite ceramic body comprising a polycrystalline silica matrix and acicular bodies of silica embedded therein.  
     
     
         28 . A light pipe for transporting light, said light pipe comprising acicular bodies of at least one scintillating material.  
     
     
         29 . A composite ceramic body comprising a ceramic matrix and acicular bodies of a least one inorganic compound, wherein said acicular bodies substantially align in direction of their longer axes.