Aluminum oxide particles

Abstract

A collection of nanoparticles of aluminum oxide have been produced by laser pyrolysis have a very narrow distribution of particle diameters. Preferably, the distribution of particle diameters effectively does not have a tail such that almost no particles have a diameter greater than about 4 times the average diameter. The pyrolysis preferably is performed by generating a molecular stream containing an aluminum precursor, an oxidizing agent and an infrared absorber. The pyrolysis can be performed with an infrared laser such as a CO 2 laser.

1 . A collection of particles comprising crystalline aluminum oxide selected from the group consisting of delta-Al 2 O 3 and theta-Al   2 O 3 , the particles having an average diameter less than about 95 nm.  
     
     
         2 . The collection of particles of  claim 1  wherein the crystalline aluminum oxide comprises delta-Al 2 O 3 .  
     
     
         3 . The collection of particles of  claim 1  wherein the particles comprise theta-Al 2 O 3 .  
     
     
         4 . The collection of particles of  claim 1  wherein the particles have an average diameter less than about 50 nm.  
     
     
         5 . The collection of particles of  claim 1  wherein the particles have an average diameter less than about 25 nm.  
     
     
         6 . The collection of particles of  claim 1  wherein the particles have an average diameter from about 5 nm to about 25 nm  
     
     
         7 . The collection of particles of  claim 1  wherein effectively no particles have a diameter greater than about four times the average diameter of the collection of particles.  
     
     
         8 . The collection of particles of  claim 1  wherein effectively no particles have a diameter greater than about three times the average diameter of the collection of particles.  
     
     
         9 . The collection of particles of  claim 1  wherein effectively no particles have a diameter greater than about two times the average diameter of the collection of particles.  
     
     
         10 . The collection of particles of  claim 1  wherein the collection of particles have a distribution of particle sizes such that at least about 95 percent of the particles have a diameter greater than about 40 percent of the average diameter and less than about 160 percent of the average diameter.  
     
     
         11 . The collection of particles of  claim 1  wherein the collection of particles have a distribution of particle sizes such that at least about 99 percent of the particles have a diameter greater than about 40 percent of the average diameter and less than about 160 percent of the average diameter.  
     
     
         12 . The collection of particles of  claim 1  wherein the collection of particles have a distribution of particle sizes such that at least about 95 percent of the particles have a diameter greater than about 60 percent of the average diameter and less than about 140 percent of the average diameter.  
     
     
         13 . A polishing composition comprising a dispersion of a collection of aluminum oxide particles of  claim 1 .  
     
     
         14 . The polishing composition of  claim 13  wherein the polishing composition comprises from about 0.05 percent by weight to about 30 percent by weight aluminum oxide particles.  
     
     
         15 . The polishing compositions of  claim 13  wherein the polishing composition comprises from about 1.0 percent by weight to about 10 percent by weight aluminum oxide particles.  
     
     
         16 . The polishing composition of  claim 13  wherein the dispersion is an aqueous dispersion.  
     
     
         17 . The polishing composition of  claim 13  wherein the dispersion is a non-aqueous dispersion.  
     
     
         18 . The polishing composition of  claim 13  further comprising abrasive particles comprising a composition selected from the group consisting of silicon carbide, metal oxides other than aluminum oxide, metal sulfides and metal carbides.  
     
     
         19 . The polishing composition of  claim 16  further comprising colloidal silica.