Abstract: Sintered product having a relative density of greater than 90%, with, to more than 80% of the volume thereof, a stack of flat ceramic platelets, the assembly of the platelets having a mean thickness of less than 3 ?m, having a width of greater than 50 mm, and including more than 20% of alumina, as a percentage on the basis of the weight of the product. The width of the product is the largest dimension measured in the plane in which the length of the product is measured, along a direction perpendicular to the direction of the length. The length of the product is the largest dimension thereof in a plane parallel to the general plane in which the platelets extend.

Abstract: Sintered product having a chemical analysis such that, in mass percentages: SiO2 content is greater than 0.2% and less than 2%, and CaO content is greater than 0.1% and less than 1.5%, and MgO content is less than 0.3%, and alumina and other elements being the complement at 100%, the content of other elements being less than 1.5%, having a relative density greater than 90%, comprising, for more than 90% of its volume, a stack of ceramic platelets (10) laid flat, all of said platelets having an average thickness less than 3 ?m, more than 95% by number of said platelets each containing more than 95% by mass of alumina, having a width (l) greater than 81 mm.

Abstract: Sintered product having a relative density of greater than 90%, with, to more than 80% of the volume thereof, a stack of flat ceramic platelets, the assembly of the platelets having a mean thickness of less than 3 ?m, having a width of greater than 50 mm, and including more than 20% of alumina, as a percentage on the basis of the weight of the product. The width of the product is the largest dimension measured in the plane in which the length of the product is measured, along a direction perpendicular to the direction of the length. The length of the product is the largest dimension thereof in a plane parallel to the general plane in which the platelets extend.

Abstract: Sintered product having a chemical analysis such that, in mass percentages: SiO2 content is greater than 0.2% and less than 2%, and CaO content is greater than 0.1% and less than 1.5%, and MgO content is less than 0.3%, and alumina and other elements being the complement at 100%, the content of other elements being less than 1.5%, having a relative density greater than 90%, comprising, for more than 90% of its volume, a stack of ceramic platelets (10) laid flat, all of said platelets having an average thickness less than 3 ?m, more than 95% by number of said platelets each containing more than 95% by mass of alumina, having a width (l) greater than 81 mm.

Abstract: The invention relates to a sintered product containing: in mass percent based on oxides, more than 99.5% of a material having a cubic crystallographic structure for more than 95% of the mass thereof, known as a material with a cubic structure, and having a refractive index of less than 2.75 in the wavelength range between 0.2 ?m and 5 ?m; and more than 50 ppma of dopants which must contain titanium oxide TiO2 and at least one additional dopant selected from ZrO2, CaO, and MgO, in which said at least one additional dopant is different from the oxide(s) forming the material with a cubic structure, but can be MgO when the material with a cubic structure is spinel MgAl2O4.

Abstract: The invention relates to a sintered product containing: in mass percent based on oxides, more than 99.5% of a material having a cubic crystallographic structure for more than 95% of the mass thereof, known as a material with a cubic structure, and having a refractive index of less than 2.75 in the wavelength range between 0.2 ?m and 5 ?m; and more than 50 ppma of dopants which must contain titanium oxide TiO2 and at least one additional dopant selected from ZrO2, CaO, and MgO, in which said at least one additional dopant is different from the oxide(s) forming the material with a cubic structure, but can be MgO when the material with a cubic structure is spinel MgAl2O4.