Systems, devices, and techniques for manufacturing a crystalline material (e.g., large crystal material) through the solid state conversion of a polycrystalline material are described. A device may be configured to concurrently heat a volume of ribbon, such as an alumina ribbon, using multiple heat sources. For example, a first heat source may heat a first volume of the ribbon and a second heat source may concurrently heat a second volume, for example, within the first volume, where the ribbon may comprise polycrystalline material. The concurrent heating may drive grain growth in the polycrystalline material in at least the second volume, which may convert the polycrystalline material to crystalline material having one or more grains that are larger than one or more grains of the polycrystalline material. The processed ribbon may include a large crystal material or a single crystal material.

Systems, devices, and techniques for manufacturing a crystalline material (e.g., large crystal material) through the solid state conversion of a polycrystalline material are described. A device may be configured to concurrently heat a volume of ribbon, such as an alumina ribbon, using multiple heat sources. For example, a first heat source may heat a first volume of the ribbon and a second heat source may concurrently heat a second volume, for example, within the first volume, where the ribbon may comprise polycrystalline material. The concurrent heating may drive grain growth in the polycrystalline material in at least the second volume, which may convert the polycrystalline material to crystalline material having one or more grains that are larger than one or more grains of the polycrystalline material. The processed ribbon may include a large crystal material or a single crystal material.

The present disclosure provides a transparent alumina-based plate, and a hot-pressing method to make the transparent alumina-based plate from platelet alumina. Alumina powder with a platelet morphology was hot-pressed to transparency with pre-load pressures of about 0-8 MPa, maximum temperatures of about 1750-1825° C., maximum pressures of about 2.5-80 MPa, and isothermal hold times of 1-7 hours. A novel alumina-based plate has been prepared, wherein the plate has a thickness of 2-5 mm, an in-line transmission of at least 60-75% for a light with a wavelength range of 645-2500 nm, an in-line transmission variance of <15% over the wavelength range of 645-2500 nm, and a relative density of 99.00-99.95%.

In one aspect, a method for fabricating metal particles is disclosed, which includes adding a plurality of metallic elements into a plasma reactor comprising a circulating fluid and two electrodes, evaporating the metallic elements to form metal vapor using plasma generated by at least one electric discharge pulse between the electrodes; and condensing the metal vapor to form metal particles. In some embodiments, the metal particles comprise metal oxide particles. In some embodiments, the metal particles are useful as part of pharmaceutical compositions or dietary supplements.

In one aspect, a method for fabricating metal particles is disclosed, which includes adding a plurality of metallic elements into a plasma reactor comprising a circulating fluid and two electrodes, evaporating the metallic elements to form metal vapor using plasma generated by at least one electric discharge pulse between the electrodes; and condensing the metal vapor to form metal particles. In some embodiments, the metal particles comprise metal oxide particles. In some embodiments, the metal particles are useful as part of pharmaceutical compositions or dietary supplements.

Systems, devices, and techniques for manufacturing a crystalline material (e.g., large crystal material) through the solid state conversion of a polycrystalline material are described. A device may be configured to concurrently heat a volume of ribbon, such as an alumina ribbon, using multiple heat sources. For example, a first heat source may heat a first volume of the ribbon and a second heat source may concurrently heat a second volume, for example, within the first volume, where the ribbon may comprise polycrystalline material. The concurrent heating may drive grain growth in the polycrystalline material in at least the second volume, which may convert the polycrystalline material to crystalline material having one or more grains that are larger than one or more grains of the polycrystalline material. The processed ribbon may include a large crystal material or a single crystal material.

A particulate material is mainly composed of alumina, has a volume average particle diameter of from 70 to 200 μm, has a degree of sphericity of from 0.89 or more to less than 0.99, has a degree of alfa-aluminization of from 40 to 85%, and produces a result of 0.017 g or less in an abrasion test for equipment.

A particulate material is mainly composed of alumina, has a volume average particle diameter of from 70 to 200 m, has a degree of sphericity of from 0.89 or more to less than 0.99, has a degree of alfa-aluminization of from 40 to 85%, and produces a result of 0.017 g or less in an abrasion test for equipment.

Sintered abrasive particles have a cellular microstructure comprising alpha alumina crystal grains of alpha alumina having a maximum dimension of less than about 3 microns are also disclosed. The sintered abrasive particles have an average particle size of less than or equal to 500 microns, and are essentially free of seed particles and alpha alumina grain size modifiers. Abrasive articles comprising a binder and a plurality of the sintered abrasive particles are also disclosed.

A method of making sintered abrasive particles includes passing alumina precursor particles through a flame under conditions such that they are converted to alpha alumina. The precursor particles comprise a precursor of alpha alumina and have an average particle size of less than or equal to 500 microns. Sintered abrasive particles have a cellular microstructure comprising alpha alumina crystal grains of alpha alumina having a maximum dimension of less than about 3 microns are also disclosed. The sintered abrasive particles have an average particle size of less than or equal to 500 microns, and are essentially free of seed particles and alpha alumina grain size modifiers. Abrasive articles comprising a binder and a plurality of the sintered abrasive particles are also disclosed.