| 摘要 |
PROBLEM TO BE SOLVED: To practically prevent the occurrence of splash even in the case of vapor deposition by an electron beam process and to form an MgO film to nearly uniform thickness. SOLUTION: The polycrystalline MgO vapor deposition material is composed of a sintered pellet 11 of polycrystalline MgO having >=99.5% MgO purity and >=96% relative density. This pellet 11 is so formed that it is edgeless or has a round edge. Further, the crystalline grain size of the pellet 11 is regulated to 1 to 500 μm. Moreover, the amounts of impurities, each by element concentration, contained in the pellet 11 are as follows: Si, <=200 ppm; Al, <=200 ppm; Ca, <=250 ppm; Zr, <=150 ppm; Fe, <=50 ppm; Cr, <=10 ppm; V, <=10 ppm; Ni, <=10 ppm; Na, <=20 ppm; K, <=20 ppm; C <=70 ppm. |
