| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a surface flashover of a ZnO element by a method wherein at least an upmost face part of a side face of a sintered body comprises a crystal layer of which a main component is ZnO of a crystal particle size smaller than the inside of the sintered body, and aγ-Bi2 O3 phase exists in a specific amount (%) or more in a crystal phase. SOLUTION: A compact of a ZnO element is filled in dies and hot-pressed and sintered in air. At this time, by a hot press pressure, in particular a locally high pressure in a contact face with a pressing jig, particle growth is suppressed and crystal particles are downsized. Herein, there exists a portion having a smaller crystal particle size than the inside of element and a thickness of about 30μm on the side-face side of the obtained ZnO element, an interface phase does not exist in particular and particle size is only changed. When represented byγ-Bi2 O3 phase amount (%)=(Iγ- Bi2 O3(321) /IZn O(101) )×100, theγ-Bi2 O3 phase exists averagely at 3% or more. Incidetally, herein, I denotes X-rays diffraction strength and () denotes miller indices Thereby, it is possible to obtain effects excellent in preventing a flashover along a face without being destructive even in an impulse resistance amount test.</p> |
