| abstract |
Polycrystals with a MgO purity of at least 99.0%, a relative density of at least 90.0%, a sulfur S content of 0.01 to 50 ppm, a chlorine Cl content of 0.01 to 50 ppm, a nitrogen N content of 0.01 to 200 ppm, and a phosphorus P content of 0.01 to 30 ppm. Even when vapor deposition is conducted using electron beam deposition, almost no splash occurs, and the film characteristics of the product MgO film can also be improved. |