Transitional alumina particulate materials having controlled morphology and processing for forming same

Abstract

An alumina particulate material is disclosed, including particles comprising transitional alumina having an aspect ratio of not less than 3:1 and an average particle size of not less than about 75 nm. Also disclosed are fabrication techniques based on seeded processing pathways.

1 . Alumina particulate material, comprising: 
 particles comprising transitional alumina having an aspect ratio of not less than 3:1 and an average particle size of not less than about 110 nm and not greater than 1000 nm.    
   
   
       2 . The particulate material of  claim 1 , wherein the transitional alumina is selected from the group consisting of gamma alumina, delta alumina, and theta alumina.  
   
   
       3 . The particulate material of  claim 2 , wherein the transitional alumina is selected from the group consisting of gamma alumina and delta alumina.  
   
   
       4 . The particulate material of  claim 3 , wherein the transitional alumina is gamma alumina.  
   
   
       5 . The particulate material of  claim 1 , wherein the particles comprise at least 70 wt % transitional alumina.  
   
   
       6 . (canceled)  
   
   
       7 . (canceled)  
   
   
       8 . (canceled)  
   
   
       9 . (canceled)  
   
   
       10 . The particulate material of  claim 1 , wherein the aspect ratio is not less than about 5:1.  
   
   
       11 . (canceled)  
   
   
       12 . (canceled)  
   
   
       13 . (canceled)  
   
   
       14 . The particulate material of  claim 1 , wherein the average particle size is not less than 125 nm.  
   
   
       15 . (canceled)  
   
   
       16 . The particulate material of  claim 1 , wherein the average particle size is not greater than about 750 nm.  
   
   
       17 . (canceled)  
   
   
       18 . (canceled)  
   
   
       19 . (canceled)  
   
   
       20 . The particulate material of  claim 1 , wherein the particles have a platy shape and a secondary aspect ratio of not less than 3:1.  
   
   
       21 . (canceled)  
   
   
       22 . (canceled)  
   
   
       23 . The particulate material of  claim 1 , wherein the particles have a needle shape and a secondary aspect ratio of not greater than 3:1.  
   
   
       24 . (canceled)  
   
   
       25 . (canceled)  
   
   
       26 . The particulate material of  claim 1 , having a specific surface area not less than about 50 m 2 /g.  
   
   
       27 . (canceled)  
   
   
       28 . The particulate material of  claim 1 , having a specific surface area not greater than about 400 m 2 /g.  
   
   
       29 . (canceled)  
   
   
       30 . The particulate material of  claim 1 , wherein the alumina particulate material is seeded alumina particulate material.  
   
   
       31 . (canceled)  
   
   
       32 . Alumina particulate material, comprising mainly: 
 seeded needle-shaped particles comprising transitional alumina having an aspect ratio of not less than 3:1, a secondary aspect ratio of not greater than 3:1, and an average particle size of not less than about 75 nm.    
   
   
       33 . The particulate material of  claim 32 , wherein the secondary aspect ratio is not greater than 2:1.  
   
   
       34 . Alumina particulate material, comprising mainly: 
 seeded platy-shaped particles comprising transitional alumina having an aspect ratio of not less than 3:1, a secondary aspect ratio of not less than 3:1, and an average particle size of not less than about 125 nm.    
   
   
       35 . The alumina particulate material of  claim 34 , wherein the secondary aspect ratio is not less than 6:1.  
   
   
       36 . A method for forming alumina particulate material, comprising: 
 providing a boehmite precursor and boehmite seeds in a suspension;    heat treating the suspension to convert the boehmite precursor into boehmite particulate material; and    calcining the boehmite particulate material to transform the boehmite particulate material into transitional alumina particulate material.    
   
   
       37 . The method of  claim 36 , wherein heat treating is carried out at a temperature greater than about 120° C.  
   
   
       38 . (canceled)  
   
   
       39 . The method of  claim 36 , wherein a weight ratio of boehmite precursor to boehmite seeds is not less 60:40.  
   
   
       40 . (canceled)  
   
   
       41 . (canceled)  
   
   
       42 . The method of  claim 36 , wherein the average particle size of the transitional alumina particulate material is not less than 75 nm.  
   
   
       43 . (canceled)  
   
   
       44 . The method of  claim 36 , wherein the average particle size is not greater than about 300 nm.  
   
   
       45 . (canceled)  
   
   
       46 . (canceled)  
   
   
       47 . (canceled)  
   
   
       48 . (canceled)  
   
   
       49 . (canceled)  
   
   
       50 . (canceled)  
   
   
       51 . (canceled)  
   
   
       52 . (canceled)  
   
   
       53 . (canceled)  
   
   
       54 . The method of  claim 36 , wherein calcination is carried out to maintain morphology of the boehmite particulate material.  
   
   
       55 . The method of  claim 54 , wherein the transitional alumina particulate has specific surface area that greater than that of the boehmite particulate material.  
   
   
       56 . (canceled)  
   
   
       57 . (canceled)  
   
   
       58 . (canceled)  
   
   
       59 . (canceled)  
   
   
       60 . (canceled)