Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree RBlaine/RBET of 3.0 to 5.5 wherein RBlaine is the particle size calculated from the Blaine specific surface area and RBET is the particle size calculated from the BET specific surface area.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×103 to 25.0×103 m2·kg?1 and a Blaine specific surface area of 2.0×103 to 7.0×103 m2·kg?1.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a Blaine specific surface area of 2.5×103 to 7.0×103 m2·kg?1 and CAA of 50 to 170 seconds.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has an adhesion water content and a hydration water content each falling in the quadrilateral region defined by the following points a to d as the vertices in a graph representing the adhesion water content-hydration water content relationship: a: adhesion water content: 0.25 mass %, hydration water content: 0.1 mass % b: adhesion water content: 0.60 mass %, hydration water content: 0.1 mass % c: adhesion water content: 0.40 mass %, hydration water content: 6.0 mass % d: adhesion water content: 0.20 mass %, hydration water content: 6.0 mass %.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree RBlaine/RBET of 3.0 to 5.5 wherein RBlaine is the particle size calculated from the Blaine specific surface area and RBET is the particle size calculated from the BET specific surface area.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×103 to 25.0×103 m2·kg?1 and a Blaine specific surface area of 2.0×103 to 7.0×103 m2·kg?1.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has an adhesion water content and a hydration water content each falling in the quadrilateral region defined by the following points a to d as the vertices in a graph representing the adhesion water content-hydration water content relationship: a: adhesion water content: 0.25 mass %, hydration water content: 0.1 mass % b: adhesion water content: 0.60 mass %, hydration water content: 0.1 mass % c: adhesion water content: 0.40 mass %, hydration water content: 6.0 mass % d: adhesion water content: 0.20 mass %, hydration water content: 6.0 mass %.

Abstract: An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a Blaine specific surface area of 2.5×103 to 7.0×103 m2·kg?1 and CAA of 50 to 170 seconds.

Abstract: Disclosed herein are a sintered magnesium oxide material which is capable of suppressing the occurrence of splashing during film formation and which is less likely to cause clogging of a supply inlet of a film formation device, a deposition material for PDP-protecting film using the same, and a process for producing the sintered material. The sintered magnesium oxide material contains magnesium oxide, 3 to 50 mass % of an oxide of a Group 2A element other than magnesium in the periodic table, and if necessary, 1000 ppm or less of one or two or more elements selected from the group consisting of aluminum, yttrium, cerium, zirconium, scandium, and chromium, and has a disk-like, elliptical plate-like, polygonal plate-like, or half-moon-like shape or a cubic or rectangular solid shape with rounded apexes.