Abstract: Alumina particles and compositions containing alumina particles are disclosed. Methods of making alumina particles and methods of using alumina particles are also disclosed.

Abstract: An aluminum oxide dispersion comprising from 30 to 99.9% (w/w) of a solvent; and from 0.1 to 70% (w/w) of aluminum oxide nanofibers suspended in the solvent, wherein the nanofibers comprise from 0 to 99.99% (w/w) of ?-AlO(OH) and from 0.01 to 100% (w/w) of ?-Al2O3; and a method of preparing the aluminum oxide dispersion.

Abstract: Aqueous dispersion containing a metal oxide powder with a fine fraction and a coarse fraction, in which—the metal oxide powder is silicon dioxide, aluminum oxide, titanium dioxide, zirconium dioxide, cerium oxide or a mixed oxide of two or more of the aforementioned metal oxides,—the fine fraction is present in aggregated form and has a mean aggregate diameter in the dispersion of less than 200 nm,—the coarse fraction consists of particles with a mean diameter of 1 to 20 ?m, —the ratio of fine fraction to coarse fraction is 2:98 to 30:70, and—the content of metal oxide powder is 50 to 85 wt. %, referred to the total amount of the dispersion. The aqueous dispersion is produced by a process comprising the steps:—production of a fine fraction dispersion by dispersing the pulverulent fine fraction in water by means of an energy input of at least 200 KJ/m3?, and—introducing the coarse fraction in the form of a powder into the fine fraction dispersion under dispersing conditions at a low energy input.

Abstract: A process for producing a stable acidic aqueous alumina sol containing columnar secondary particles having a length of 50 to 400 nm which are formed by face-to-face coagulation of rectangular plate-like primary particles having a length of one side of 10 to 40 nm and a thickness of 2.5 to 10 nm when observed through an electron microscope, by use of an aqueous alkali aluminate solution and liquid or gaseous carbon dioxide as starting materials. The obtained acidic aqueous alumina sol has a low viscosity and is stable for salts. The dried gel obtained from the sol is characterized in that the gel structure thereof is rigid even though it is porous.

Abstract: Disclosed herein is a recording medium comprising an alumina hydrate having an average pore radius of 20 to 200 Å and a half breadth of pore radius distribution of 20 to 150 Å.